Leetcode Unique Paths II

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.

[
  [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.

簡單的動態規劃問題

class Solution {
public:
    int dp[102][102];
    int uniquePathsWithObstacles(vector<vector<int> > &obstacleGrid) {
        memset(dp,0,sizeof(dp));
        dp[0][0]=obstacleGrid[0][0] == 1 ? 0:1;
        int n = obstacleGrid.size(), m = obstacleGrid[0].size();
        for(int i = 1; i < n; ++ i )
            dp[i][0] = obstacleGrid[i][0] == 1 ? 0 : dp[i-1][0];
        for(int i = 1; i < m; ++ i )
            dp[0][i] = obstacleGrid[0][i] == 1 ? 0 : dp[0][i-1];
        for(int i = 1; i < n ; ++ i){
            for(int j = 1; j <  m ; ++ j){
                dp[i][j] = obstacleGrid[i][j] == 1 ? 0 : dp[i-1][j] + dp[i][j-1];   
            }
        }
        return dp[n-1][m-1];
    }
};