LeetCode | 63. 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.

思路：简单动态规划，grid[ i ][ j ]为1时，dp[ i ][ j ] = 0

class Solution {public:    int uniquePathsWithObstacles(vector<vector<int>>& grid) {        int m = grid.size(), n = grid[0].size();        int dp[110][110];        //处理第一列        for(int i=0;i<m;i++)        {            if(grid[i][0] == 1)            {                dp[i][0] = 0;                for(int j=i;j<m;j++)                    dp[j][0] = 0;                break;            }            else                dp[i][0] = 1;        }        //处理第一行        for(int i=0;i<n;i++)        {            if(grid[0][i] == 1)            {                dp[0][i] = 0;                for(int j=i;j<n;j++)                    dp[0][j] = 0;                break;            }            else                dp[0][i] = 1;        }        //处理中间部分        for(int i=1;i<m;i++)        {            for(int j=1;j<n;j++)            {                if(grid[i][j] == 1)                    dp[i][j] = 0;                else                {                    dp[i][j] = dp[i-1][j] + dp[i][j-1];                }            }        }        return dp[m-1][n-1];    }};