Unique Paths II

Desicription

Follow up for “Unique Paths”:

Now consider if some obstacles are added to the grids. How many unique paths would there be?

An obstacle and empty space is marked as 1 and 0 respectively in the grid.

For example,
There is one obstacle in the middle of a 3x3 grid as illustrated below.

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[
[0,0,0],
[0,1,0],
[0,0,0]
]

The total number of unique paths is 2.

Note: m and n will be at most 100.

Solution

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class Solution {
public:
int uniquePathsWithObstacles(vector<vector<int>>& obstacleGrid) {
int n = obstacleGrid.size();
int m = obstacleGrid[0].size();
vector<vector<int>> dp(n+1, vector<int>(m+1, 0));
dp[0][1] = 1;
for(int i = 1; i <= n; i++){
for(int j = 1; j <= m; j++){
if(!obstacleGrid[i-1][j-1]){
dp[i][j] = dp[i-1][j] + dp[i][j-1];
}
}
}
return dp[n][m];
}
};