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  • [LeetCode] Unique Paths II(DP)

    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.

    class Solution {
    public:
        int uniquePathsWithObstacles(vector<vector<int> > &obstacleGrid) {
            int rows = obstacleGrid.size();
            if(rows<1)
                return rows;
            int cols  = obstacleGrid[0].size();
            if(cols<1)
                return cols;
            vector<int> temp(cols,1);
            vector<vector<int> > res(rows,temp);//res记录到达相应位置的路径条数
            for(int i = 0;i<rows;i++){
                for(int j=0;j<cols;j++){
                   if(obstacleGrid[i][j]==1)
                     res[i][j] = 0;
                   else if(i==0 && j!=0)
                     res[i][j] = res[i][j-1];
                   else if(j==0 && i!=0)
                     res[i][j] = res[i-1][j];
                   else if(i!=0 && j!=0)
                     res[i][j] = res[i-1][j]+res[i][j-1];
                }
            
            }//end for
            return res[rows-1][cols-1];
        }
    };
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  • 原文地址:https://www.cnblogs.com/Xylophone/p/3892414.html
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