leetcode@ [62/63] Unique Paths II

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