https://leetcode.com/problems/01-matrix/ — class Solution { public int[][] updateMatrix(int[][] matrix) { if(matrix == null || matrix.length == 0 || matrix[0].length == 0) return matrix; int m = matrix.length; int n = matrix[0].length; int[][] dist = new int[m][n]; for(int[] a : dist) { Arrays.fill(a, 10001); } for(int i = 0; i < m; i++) { for(int j = 0; j< n; j++) { if(matrix[i][j] == 0) { dist[i][j] = 0; } else { if(i > 0) { dist[i][j] = Math.min(dist[i-1][j] + 1, dist[i][j]); } if(j > 0) { dist[i][j] = Math.min(dist[i][j-1] + 1, dist[i][j]); } } } } for(int i = m-1; i >= 0; i--) { for(int j = n-1; j >= 0; j--) { if(i < m-1) { dist[i][j] = Math.min(dist[i+1][j] + 1, dist[i][j]); } if(j < n-1){ dist[i][j] = Math.min(dist[i][j+1] + 1, dist[i][j]); } } } return dist; } }

https://leetcode.com/problems/palindromic-substrings/ — Solution 1 class Solution { public int countSubstrings(String s) { int n = s.length(); int ans = n…

https://leetcode.com/problems/longest-common-subsequence/ — class Solution { public int longestCommonSubsequence(String text1, String text2) { int n = text1.length(); int m = text2.length(); char[] st1 = text1.toCharArray(); char[] st2 = text2.toCharArray(); int[][] dp = new int[n+1][m+1]; for (int i = 1; i <= n; ++i) { for (int j = 1; j <= m; ++j) { if (st1[i-1] == st2[j-1]) { dp[i][j] = dp[i-1][j-1] + 1; } else { dp[i][j] = Math.max(dp[i-1][j], dp[i][j-1]); } } } return dp[n][m]; } }

https://leetcode.com/problems/last-stone-weight/ — class Solution { public int lastStoneWeight(int[] stones) { if(stones == null || stones.length == 0) return 0; PriorityQueue<Integer> pq = new PriorityQueue<>((a,b)-> b-a); for(int stone: stones) { pq.offer(stone); } while(!pq.isEmpty()) { int s1 = pq.poll(); if(!pq.isEmpty()){ int s2 = pq.poll(); if (s1 > s2) pq.offer(s1 - s2); } else { return s1; } } return 0; } }

https://leetcode.com/problems/minimum-falling-path-sum-ii/ — class Solution { public int minFallingPathSum(int[][] arr) { if (arr == null || arr.length == 0 || arr[0].length == 0) return 0; int n = arr.length; int min1, min2, minCol = 0; for (int i = n - 2; i >= 0; i--) { min1 = Integer.MAX_VALUE; min2 = Integer.MAX_VALUE; for (int j = 0; j < n; j++) { if (arr[i + 1][j] < min1) { min2 = min1; min1 = arr[i + 1][j]; minCol = j; } else if (arr[i + 1][j] < min2) { min2 = arr[i + 1][j]; } } for (int j = 0; j < n; j++) { if (j == minCol) arr[i][j] += min2; else arr[i][j] += min1; } } int result = Integer.MAX_VALUE; for (int i = 0; i < n; i++) { result = Math.min(result, arr[0][i]); } return result; } }

https://leetcode.com/problems/minimum-falling-path-sum/ — class MinFallingPathSum{ public int minFallingPathSumMethod(int[][] A) { if(A == null || A.length == 0 || A[0].length == 0) return 0; int n = A.length; for(int i = 1; i < n; i++) { for(int j = 0; j < n; j++) { int min = A[i-1][j]; if(j > 0) min = Math.min(min, A[i-1][j-1]); if(j < n-1) min = Math.min(min, A[i-1][j+1]); A[i][j] += min; } } int result = Integer.MAX_VALUE; for(int i : A[n-1]) { result = Math.min(i, result); } return result; } }

https://leetcode.com/problems/unique-paths-iii/ — class Solution { int rows = 0; int cols = 0; int count_zero = 0; public int uniquePathsIII(int[][] grid) {…

https://leetcode.com/problems/unique-paths/ — class Solution { public int uniquePaths(int m, int n) { if(m == 0 || n == 0) return 0; int[][] grid = new int[m][n]; //fill all cells with 1. This will eventually be updated for(int[] ar: grid) { Arrays.fill(ar, 1); } for(int i = 1 ; i < m; i++){ for(int j = 1 ; j < n ; j++) { grid[i][j] = grid[i-1][j] + grid [i][j-1]; } } return grid[m-1][n-1]; } }

https://leetcode.com/problems/min-cost-climbing-stairs/ — class Solution { public int minCostClimbingStairs(int[] cost) { if(cost == null) return 0; if(cost.length ==1 ) return cost[0]; int t0 = cost[0]; int t1 = cost[1]; for(int i=2; i < cost.length ; i++ ) { int t2 = Math.min(t0, t1) +cost[i]; t0=t1; t1=t2; } return Math.min(t0, t1); } }