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：动态规划 class Solution { public: int uniquePathsWithObstacles(vector<vector<int>>& obstacleGrid) { int m = obstacleGrid.size(); if(m == 0){ return 0; } int n = obstacleGrid[0].size(); int matrix[m][n] = {0}; //初始化 bool flag = true; for(int i = 0; i < n; i++){ if(obstacleGrid[0][i] == 0 && flag) matrix[0][i] = 1; else{ flag = false; matrix[0][i] = 0; } } flag = true; for(int i = 0; i < m; i++){ if(obstacleGrid[i][0] == 0 && flag) matrix[i][0] = 1; else{ flag = false; matrix[i][0] = 0; } } // for(int i = 1; i < m; i++){ for(int j = 1; j < n; j++){ if(obstacleGrid[i][j] == 1) matrix[i][j] = 0; else matrix[i][j] = matrix[i-1][j] + matrix[i][j-1]; } } return matrix[m-1][n-1]; } };