Create 0931-minimum-falling-path-sum.java

Author: sujal-goswami

java/0931-minimum-falling-path-sum.java

@@ -0,0 +1,59 @@
+/*----------------------------------
+  Time Complexity: O(n^2)
+  Space Complexity: (1)
+----------------------------------*/ 
+
+class Solution {
+    public int minFallingPathSum(int[][] matrix) {
+        int N = matrix.length;
+
+        for(int r = 1; r < N; r++){
+            for(int c = 0; c < N; c++){
+                int mid = matrix[r-1][c];
+                int left = (c > 0)? matrix[r-1][c-1]: Integer.MAX_VALUE;
+                int right = (c < N-1)? matrix[r-1][c+1]: Integer.MAX_VALUE;
+                matrix[r][c] = matrix[r][c] + Math.min(left, Math.min(mid, right));
+            }
+        }
+        int res = Integer.MAX_VALUE;
+        for(int i = 0; i < N; i++){
+            res = Math.min(res, matrix[N-1][i]);
+        }
+        return res;
+    }
+}
+
+/*----------------------------------
+  Time Complexity: O(n^2)
+  Space Complexity: (n^2)
+----------------------------------*/  
+
+class Solution {
+    public int minFallingPathSum(int[][] matrix) {
+        int n = matrix.length;
+        int[][] dp = new int[n+1][n+1];
+
+        for(int i = n-1; i >= 0; i--){
+            for(int j = 0; j < n; j++){
+                if(j == 0)
+                    dp[i][j] = matrix[i][j] + Math.min(dp[i+1][j], dp[i+1][j+1]);
+                else if (j == n-1) {
+                    dp[i][j] = matrix[i][j] + Math.min(dp[i+1][j-1], dp[i+1][j]);
+                } else{
+                    int min = dp[i+1][j-1];
+                    if(dp[i+1][j] < min)
+                        min = dp[i+1][j];
+                    if(dp[i+1][j+1] < min)
+                        min = dp[i+1][j+1];
+
+                    dp[i][j] = matrix[i][j] + min;
+                }
+            }
+        }
+        int res = Integer.MAX_VALUE;
+        for(int i=0; i<n; i++)
+            res = Math.min(res, dp[0][i]);
+
+        return res;    
+    }
+}