Create 63. Unique Path II

Author: stone16

63. Unique Path II

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+public class Solution {
+    public int uniquePathsWithObstacles(int[][] obstacleGrid) {
+        //  int m = obstacleGrid.length;
+        //  int n = obstacleGrid[0].length;
+        // // use dp
+
+        // Integer[][] map = new Integer[m][n];
+        
+        // if(obstacleGrid[0][0] == 1){
+        //     return 0;
+        // }else{
+        //     map[0][0] = 1;
+        // }
+        
+        // for(int i = 1; i<m;i++){
+        //     if(map[i-1][0] != 0){
+        //         map[i][0] = 1;
+        //     }
+        //     if(obstacleGrid[i][0] == 1){
+        //         map[i][0] = 0;
+        //     }
+        // }
+        // for(int j= 1;j<n;j++){
+        //     if(map[0][j-1] != 0){
+        //       map[0][j] = 1; 
+        //     }
+        //     if(obstacleGrid[0][j] == 1){
+        //         map[0][j] = 0;
+        //     }
+        // }
+        // for(int i = 1;i < m;i++){
+        //     for(int j = 1; j < n;j++){
+        //         if(i != 0 && j!= 0)
+        //             map[i][j] = map[i-1][j] + map[i][j-1];
+        //         if(obstacleGrid[i][j] == 1){
+        //             map[i][j] = 0;
+        //         }
+        //     }
+        // }
+        // return map[m-1][n-1];
+        
+         //Empty case
+        if(obstacleGrid.length == 0) return 0;
+        
+        int rows = obstacleGrid.length;
+        int cols = obstacleGrid[0].length;
+        
+        for(int i = 0; i < rows; i++){
+            for(int j = 0; j < cols; j++){
+                if(obstacleGrid[i][j] == 1)
+                    obstacleGrid[i][j] = 0;
+                else if(i == 0 && j == 0)
+                    obstacleGrid[i][j] = 1;
+                else if(i == 0)
+                    obstacleGrid[i][j] = obstacleGrid[i][j - 1] * 1;// For row 0, if there are no paths to left cell, then its 0,else 1
+                else if(j == 0)
+                    obstacleGrid[i][j] = obstacleGrid[i - 1][j] * 1;// For col 0, if there are no paths to upper cell, then its 0,else 1
+                else
+                    obstacleGrid[i][j] = obstacleGrid[i - 1][j] + obstacleGrid[i][j - 1];
+            }
+        }
+        
+        return obstacleGrid[rows - 1][cols - 1];
+    
+    }
+}