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Commit fdb0087

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[Function add]
1. Add leetcode solutions with amazon tag.
1 parent 9114e28 commit fdb0087

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‎leetcode/45. Jump Game II.md

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@@ -58,4 +58,33 @@ class Solution {
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return result;
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}
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}
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```
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```
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### Amazon Session
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* Method 1: Greedy
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```Java
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class Solution {
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public int jump(int[] nums) {
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//[2,3,1,1,4]
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if(nums.length <= 1) return 0;
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if(nums[0] >= nums.length - 1) return 1;
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int res = 1, cur = 0, max = 0;
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while(max < nums.length - 1){
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int nextCur = 0;
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int nextMax = 0;
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max = cur + nums[cur];
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for(int i = cur + 1; i <= max && i < nums.length; i++){
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if(i + nums[i] > nextMax){
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nextCur = i;
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nextMax = i + nums[i];
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}
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}
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cur = nextCur;
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max = nextMax;
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if(max >= nums.length - 1) return res + 1;
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res++;
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}
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return res;
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}
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}
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```

‎leetcode/79. Word Search.md

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@@ -215,3 +215,45 @@ class Solution {
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}
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}
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```
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### Amazon Session
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* Method 1: dfs
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```Java
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class Solution {
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private static final int[][] dir = new int[][]{{0, 1}, {0, -1}, {1, 0}, {-1, 0}};
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private char[][] board;
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private int height, width;
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private String word;
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public boolean exist(char[][] board, String word) {
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if(board == null || board.length == 0 || board[0].length == 0) return false;
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this.board = board;
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this.height = board.length;
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this.width = board[0].length;
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this.word = word;
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for(int i = 0; i < height; i++){
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for(int j = 0; j < width; j++){
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if(word.charAt(0) == board[i][j]){
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Set<Integer> visited = new HashSet<>();
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visited.add(i * width + j);
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if(dfs(i, j, visited, 0)) return true;
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}
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}
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}
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return false;
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}
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private boolean dfs(int x, int y, Set<Integer> visited, int index){
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if(index == word.length() - 1) return true;
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int tx = 0, ty = 0;
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for(int d = 0; d < 4; d++){
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tx = x + dir[d][0];
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ty = y + dir[d][1];
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if(tx >= 0 && tx < height && ty >= 0 && ty < width && !visited.contains(tx * width + ty) && board[tx][ty] == word.charAt(index + 1)){
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visited.add(tx * width + ty);
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if(dfs(tx, ty, visited, index + 1)) return true;
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visited.remove(tx * width + ty);
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}
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}
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return false;
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}
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}
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```
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## 992. Subarrays with K Different Integers
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### Question
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Given an array A of positive integers, call a (contiguous, not necessarily distinct) subarray of A good if the number of different integers in that subarray is exactly K.
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(For example, [1,2,3,1,2] has 3 different integers: 1, 2, and 3.)
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Return the number of good subarrays of A.
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```
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Example 1:
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Input: A = [1,2,1,2,3], K = 2
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Output: 7
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Explanation: Subarrays formed with exactly 2 different integers: [1,2], [2,1], [1,2], [2,3], [1,2,1], [2,1,2], [1,2,1,2].
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Example 2:
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Input: A = [1,2,1,3,4], K = 3
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Output: 3
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Explanation: Subarrays formed with exactly 3 different integers: [1,2,1,3], [2,1,3], [1,3,4].
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```
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Note:
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1. 1 <= A.length <= 20000
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2. 1 <= A[i] <= A.length
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3. 1 <= K <= A.length
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### Thinking:
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* Method1:
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1. atMost(A, K), number of subarrays with at most K elements in A.
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2. atMost(A, K) - atMost(A, K - 1): sub-array with exactly K elements.
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```Java
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class Solution {
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public int subarraysWithKDistinct(int[] A, int K) {
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return atMost(A, K) - atMost(A, K - 1);
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}
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private int atMost(int[] A, int k){
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Map<Integer, Integer> map = new HashMap<>();
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int slow = 0, fast = 0;
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int res = 0;
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while(fast < A.length){
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if(!map.containsKey(A[fast])) k--;
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map.put(A[fast], map.getOrDefault(A[fast], 0) + 1);
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while(k < 0){
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int cur = map.get(A[slow]);
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if(cur == 1){
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map.remove(A[slow]);
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k++;
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}else map.put(A[slow], cur - 1);
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slow++;
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}
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res += fast - slow + 1;
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++fast;
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}
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return res;
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}
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}
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```
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### Reference
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1. [[Java/C++/Python] Sliding Window with Video](https://leetcode.com/problems/subarrays-with-k-different-integers/discuss/234482/JavaC++Python-Sliding-Window-with-Video)

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