Problem Description
You are given an m x n integer array grid. There is a robot initially located at the top-left corner (i.e., grid[0][0]). The robot tries to move to the bottom-right corner (i.e., grid[m - 1][n - 1]). The robot can only move either down or right at any point in time.
An obstacle and space are marked as 1 or 0 respectively in grid. A path that the robot takes cannot include any square that is an obstacle.
Return the number of possible unique paths that the robot can take to reach the bottom-right corner.
Solution
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class Solution {
public int uniquePathsWithObstacles(int[][] A) {
int n = A.length;
int m = A[0].length;
int[][] dp = new int[n][m];
if(A[0][0] == 1) return 0;
dp[0][0] = 1;
for(int i=0; i<n; i++){
if(A[i][0] == 1) break;
dp[i][0] = 1;
}
for(int i=0; i<m; i++){
if(A[0][i] == 1) break;
dp[0][i] = 1;
}
for(int i=1; i<n; i++){
for(int j=1; j<m; j++){
if(A[i][j] == 1){
continue;
}
dp[i][j] = dp[i-1][j] + dp[i][j-1];
}
}
return dp[n-1][m-1];
}
}