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Commit 6e208bd

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Added tasks 207-209.
1 parent bfd26d2 commit 6e208bd

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6 files changed

+203
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lines changed

6 files changed

+203
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lines changed
Lines changed: 41 additions & 0 deletions
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package g0201_0300.s0207_course_schedule;
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import java.util.ArrayList;
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@SuppressWarnings("unchecked")
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public class Solution {
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private static final int WHITE = 0;
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private static final int GRAY = 1;
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private static final int BLACK = 2;
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public boolean canFinish(int numCourses, int[][] prerequisites) {
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ArrayList<Integer>[] adj = new ArrayList[numCourses];
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for (int i = 0; i < numCourses; i++) {
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adj[i] = new ArrayList<>();
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}
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for (int[] pre : prerequisites) {
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adj[pre[1]].add(pre[0]);
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}
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int[] colors = new int[numCourses];
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for (int i = 0; i < numCourses; i++) {
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if (colors[i] == WHITE && !adj[i].isEmpty() && hasCycle(adj, i, colors)) {
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return false;
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}
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}
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return true;
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}
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private boolean hasCycle(ArrayList<Integer>[] adj, int node, int[] colors) {
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colors[node] = GRAY;
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for (int nei : adj[node]) {
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if (colors[nei] == GRAY) {
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return true;
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}
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if (colors[nei] == WHITE && hasCycle(adj, nei, colors)) {
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return true;
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}
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}
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colors[node] = BLACK;
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return false;
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}
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}
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package g0201_0300.s0208_implement_trie_prefix_tree;
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@SuppressWarnings("java:S1104")
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public class Trie {
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static class TrieNode {
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// Initialize your data structure here.
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public TrieNode[] children;
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public boolean isWord;
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public TrieNode() {
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children = new TrieNode[26];
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}
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}
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private TrieNode root;
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private boolean startWith;
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public Trie() {
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root = new TrieNode();
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}
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// Inserts a word into the trie.
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public void insert(String word) {
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insert(word, root, 0);
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}
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private void insert(String word, TrieNode root, int idx) {
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if (idx == word.length()) {
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root.isWord = true;
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return;
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}
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int index = word.charAt(idx) - 'a';
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if (root.children[index] == null) {
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root.children[index] = new TrieNode();
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}
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insert(word, root.children[index], idx + 1);
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}
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// Returns if the word is in the trie.
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public boolean search(String word) {
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return search(word, root, 0);
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}
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public boolean search(String word, TrieNode root, int idx) {
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if (idx == word.length()) {
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startWith = true;
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return root.isWord;
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}
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int index = word.charAt(idx) - 'a';
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if (root.children[index] == null) {
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startWith = false;
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return false;
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}
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return search(word, root.children[index], idx + 1);
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}
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// Returns if there is any word in the trie
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// that starts with the given prefix.
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public boolean startsWith(String prefix) {
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search(prefix);
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return startWith;
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}
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}
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package g0201_0300.s0209_minimum_size_subarray_sum;
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public class Solution {
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public int minSubArrayLen(int target, int[] nums) {
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int i = 0;
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int j = 0;
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int sum = 0;
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int min = Integer.MAX_VALUE;
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while (j < nums.length) {
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sum += nums[j];
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if (sum < target) {
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j++;
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} else {
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while (i <= j) {
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if (sum - nums[i] >= target) {
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sum = sum - nums[i];
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i++;
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} else {
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break;
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}
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}
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if (j - i + 1 < min) {
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min = j - i + 1;
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}
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j++;
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}
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}
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if (min == Integer.MAX_VALUE) {
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return 0;
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}
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return min;
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}
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}
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package g0201_0300.s0207_course_schedule;
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import static org.hamcrest.CoreMatchers.equalTo;
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import static org.hamcrest.MatcherAssert.assertThat;
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import org.junit.Test;
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public class SolutionTest {
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@Test
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public void canFinish() {
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assertThat(new Solution().canFinish(2, new int[][] {{1, 0}}), equalTo(true));
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}
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@Test
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public void canFinish2() {
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assertThat(new Solution().canFinish(2, new int[][] {{1, 0}, {0, 1}}), equalTo(false));
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}
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}
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package g0201_0300.s0208_implement_trie_prefix_tree;
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import static org.hamcrest.CoreMatchers.equalTo;
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import static org.hamcrest.MatcherAssert.assertThat;
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import org.junit.Test;
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public class TrieTest {
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@Test
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public void trie() {
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Trie trie = new Trie();
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trie.insert("apple");
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// return True
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assertThat(trie.search("apple"), equalTo(true));
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// return False
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assertThat(trie.search("app"), equalTo(false));
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// return True
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assertThat(trie.startsWith("app"), equalTo(true));
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trie.insert("app");
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// return True
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assertThat(trie.search("app"), equalTo(true));
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}
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}
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package g0201_0300.s0209_minimum_size_subarray_sum;
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import static org.hamcrest.CoreMatchers.equalTo;
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import static org.hamcrest.MatcherAssert.assertThat;
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import org.junit.Test;
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public class SolutionTest {
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@Test
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public void minSubArrayLen() {
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assertThat(new Solution().minSubArrayLen(7, new int[] {2, 3, 1, 2, 4, 3}), equalTo(2));
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}
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@Test
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public void minSubArrayLen2() {
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assertThat(new Solution().minSubArrayLen(4, new int[] {1, 4, 4}), equalTo(1));
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}
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@Test
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public void minSubArrayLen3() {
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assertThat(
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new Solution().minSubArrayLen(11, new int[] {1, 1, 1, 1, 1, 1, 1, 1}), equalTo(0));
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}
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}

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