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Commit 5408c98

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Checkin code
1 parent 7519c3e commit 5408c98

14 files changed

+733
-0
lines changed

‎src/conclusion/DecodeString.java

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package conclusion;
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import java.util.Stack;
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public class DecodeString {
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public String decodeString(String s) {
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StringBuilder res = new StringBuilder();
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Stack<Integer> countStack = new Stack<>();
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Stack<String> resStack = new Stack<>();
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int idx = 0;
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while (idx < s.length()) {
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if (Character.isDigit(s.charAt(idx))) {
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int count = 0;
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while (Character.isDigit(s.charAt(idx))) {
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count = 10 * count + (s.charAt(idx) - '0');
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idx++;
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}
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countStack.push(count);
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} else if (s.charAt(idx) == '[') {
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resStack.push(res.toString());
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res.delete(0, res.length());
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idx++;
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} else if (s.charAt(idx) == ']') {
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StringBuilder temp = new StringBuilder(resStack.pop());
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int repeatTimes = countStack.pop();
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for (int i = 0; i < repeatTimes; i++) {
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temp.append(res);
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}
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res.delete(0, res.length());
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res.append(temp);
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idx++;
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} else {
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res.append(s.charAt(idx++));
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}
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}
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return res.toString();
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}
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}

‎src/conclusion/FloodFill.java

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package conclusion;
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public class FloodFill {
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public int[][] floodFill(int[][] image, int sr, int sc, int newColor) {
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int color = image[sr][sc];
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if (color != newColor)
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dfs(image, sr, sc, color, newColor);
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return image;
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}
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public void dfs(int[][] image, int r, int c, int color, int newColor) {
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if (image[r][c] == color) {
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image[r][c] = newColor;
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if (r >= 1)
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dfs(image, r - 1, c, color, newColor);
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if (c >= 1)
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dfs(image, r, c - 1, color, newColor);
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if (r + 1 < image.length)
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dfs(image, r + 1, c, color, newColor);
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if (c + 1 < image[0].length)
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dfs(image, r, c + 1, color, newColor);
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}
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}
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}

‎src/conclusion/KeysAndRooms.java

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package conclusion;
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import java.util.HashSet;
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import java.util.List;
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import java.util.Stack;
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public class KeysAndRooms {
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public boolean canVisitAllRooms(List<List<Integer>> rooms) {
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int n = rooms.size();
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if (n <= 1)
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return true;
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HashSet<Integer> set = new HashSet<Integer>();
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Stack<Integer> st = new Stack<Integer>();
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st.push(0);
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set.add(0);
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while (!st.isEmpty()) {
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for (int key : rooms.get(st.pop())) {
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if (!set.contains(key)) {
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set.add(key);
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st.push(key);
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}
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}
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}
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return set.size() == n;
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}
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}

‎src/conclusion/Matrix01.java

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package conclusion;
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public class Matrix01 {
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public int[][] updateMatrix(int[][] matrix) {
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if (matrix.length == 0 || matrix[0].length == 0) {
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return matrix;
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}
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int range = matrix.length * matrix[0].length;
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for (int i = 0; i < matrix.length; i++) {
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for (int j = 0; j < matrix[0].length; j++) {
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if (matrix[i][j] != 0) {
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int upCell = (i > 0) ? matrix[i - 1][j] : range;
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int leftCell = (j > 0) ? matrix[i][j - 1] : range;
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matrix[i][j] = Math.min(upCell, leftCell) + 1;
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}
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}
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}
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for (int i = matrix.length - 1; i >= 0; i--) {
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for (int j = matrix[0].length - 1; j >= 0; j--) {
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if (matrix[i][j] != 0) {
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int downCell = (i < matrix.length - 1) ? matrix[i + 1][j] : range;
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int rightCell = (j < matrix[0].length - 1) ? matrix[i][j + 1] : range;
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matrix[i][j] = Math.min(Math.min(downCell, rightCell) + 1, matrix[i][j]);
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}
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}
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}
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return matrix;
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}
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}

‎src/conclusion/QueueUsingStack.java

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package conclusion;
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import java.util.Stack;
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public class QueueUsingStack {
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public class usingStackGet {
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Stack<Integer> st;
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int first, size;
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/** Initialize your data structure here. */
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public usingStackGet() {
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st = new Stack<Integer>();
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first = 0;
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size = 0;
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}
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/** Push element x to the back of queue. */
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public void push(int x) {
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st.push(x);
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size++;
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}
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/** Removes the element from in front of queue and returns that element. */
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public int pop() {
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size--;
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int res = st.get(first);
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first++;
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return res;
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}
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/** Get the front element. */
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public int peek() {
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return st.get(first);
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}
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/** Returns whether the queue is empty. */
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public boolean empty() {
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return size == 0;
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}
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}
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public class MyQueue {
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Stack<Integer> s1, s2;
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int first;
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/** Initialize your data structure here. */
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public MyQueue() {
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s1 = new Stack<Integer>();
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s2 = new Stack<Integer>();
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}
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/** Push element x to the back of queue. */
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public void push(int x) {
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if (s1.isEmpty())
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first = x;
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s1.push(x);
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}
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/** Removes the element from in front of queue and returns that element. */
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public int pop() {
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if (s2.isEmpty()) {
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while (!s1.isEmpty())
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s2.push(s1.pop());
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}
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return s2.pop();
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}
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/** Get the front element. */
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public int peek() {
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if (s2.isEmpty())
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return first;
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return s2.peek();
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}
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/** Returns whether the queue is empty. */
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public boolean empty() {
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return (s1.isEmpty() && s2.isEmpty());
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}
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}
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}
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/**
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* Your MyQueue object will be instantiated and called as such: MyQueue obj =
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* new MyQueue(); obj.push(x); int param_2 = obj.pop(); int param_3 =
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* obj.peek(); boolean param_4 = obj.empty();
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*/

‎src/conclusion/StackUsingQueues.java

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package conclusion;
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import java.util.LinkedList;
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import java.util.Queue;
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public class StackUsingQueues {
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Queue<Integer> q1;
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int size;
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/** Initialize your data structure here. */
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public StackUsingQueues() {
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q1 = new LinkedList<Integer>();
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}
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/** Push element x onto stack. */
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public void push(int x) {
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q1.add(x);
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size = q1.size();
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while(size-- > 1) {
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q1.add(q1.poll());
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}
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}
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/** Removes the element on top of the stack and returns that element. */
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public int pop() {
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return q1.poll();
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}
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/** Get the top element. */
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public int top() {
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return q1.peek();
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}
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/** Returns whether the stack is empty. */
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public boolean empty() {
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return (q1.isEmpty());
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}
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}
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/**
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* Your MyStack object will be instantiated and called as such: MyStack obj =
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* new MyStack(); obj.push(x); int param_2 = obj.pop(); int param_3 = obj.top();
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* boolean param_4 = obj.empty();
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*/

‎src/queue/MyCircularQueue.java

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package queue;
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public class MyCircularQueue {
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int[] q;
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int head = 0, tail = -1, n = 0;
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/** Initialize your data structure here. Set the size of the queue to be k. */
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public MyCircularQueue(int k) {
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q = new int[k];
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}
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/** Insert an element into the circular queue. Return true if the operation is successful. */
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public boolean enQueue(int value) {
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if (isFull())
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return false;
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if (tail == q.length - 1)
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tail = -1;
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q[++tail] = value;
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n++;
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return true;
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}
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/** Delete an element from the circular queue. Return true if the operation is successful. */
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public boolean deQueue() {
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if (isEmpty())
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return false;
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if (head == q.length - 1) {
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head = 0;
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n--;
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return true;
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}
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head++; n--;
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return true;
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}
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/** Get the front item from the queue. */
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public int Front() {
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if (isEmpty())
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return -1;
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return q[head];
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}
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/** Get the last item from the queue. */
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public int Rear() {
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if (isEmpty())
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return -1;
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return q[tail];
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}
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/** Checks whether the circular queue is empty or not. */
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public boolean isEmpty() {
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return n <= 0;
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}
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/** Checks whether the circular queue is full or not. */
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public boolean isFull() {
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return n >= q.length;
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}
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}
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/**
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* Your MyCircularQueue object will be instantiated and called as such:
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* MyCircularQueue obj = new MyCircularQueue(k);
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* boolean param_1 = obj.enQueue(value);
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* boolean param_2 = obj.deQueue();
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* int param_3 = obj.Front();
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* int param_4 = obj.Rear();
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* boolean param_5 = obj.isEmpty();
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* boolean param_6 = obj.isFull();
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*/

‎src/queue/NumberOfIslands.java

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package queue;
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public class NumberOfIslands {
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int n = 0, m = 0;
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public int numIslands(char[][] grid) {
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n = grid.length;
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if (n == 0)
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return 0;
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m = grid[0].length;
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int c = 0;
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for (int i = 0; i < n; ++i) {
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for (int j = 0; j < m; ++j) {
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if (grid[i][j] == '1') {
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explore(grid, i, j);
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c++;
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}
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}
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}
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return c;
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}
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public void explore(char[][] grid, int i, int j) {
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if (i < 0 || j < 0 || i >= n || j >= m || grid[i][j] != '1')
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return;
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grid[i][j] = 0;
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explore(grid, i + 1, j);
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explore(grid, i - 1, j);
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explore(grid, i, j + 1);
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explore(grid, i, j - 1);
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}
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}

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