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  • 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]
    ]
    
    he total number of unique paths is 2.
    
    Note: m and n will be at most 100.
    

      同Unique Paths的DP类似。

    class Solution {
    public:
        int uniquePathsWithObstacles(vector<vector<int> > &obstacleGrid) {
            // Start typing your C/C++ solution below
            // DO NOT write int main() function
            int m = obstacleGrid.size();
            int n = obstacleGrid[0].size();
            vector<vector<int>> grid(m, vector<int>(n,0));
            for(int i = 0; i< n; i++)
                if(obstacleGrid[0][i] ==0) grid[0][i] = 1;
                else break;
            for(int i = 0; i< m; i++)
                if(obstacleGrid[i][0] == 0) grid[i][0] = 1;
                else break;
                
            for(int i = 1; i< m; i++)
              for(int j = 1; j< n; j++)
                    if(obstacleGrid[i][j] == 0)
                       grid[i][j] = grid[i-1][j] + grid[i][j-1];
            
            return grid[m-1][n-1];
        }
    };
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  • 原文地址:https://www.cnblogs.com/graph/p/3258555.html
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