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.
answer:
class Solution {public:    int uniquePathsWithObstacles(vector<vector<int>>& obstacleGrid) {        int result = 0;        if(obstacleGrid.size() == 0) return result;        int m = obstacleGrid.size(),n = obstacleGrid[0].size();        cout << m << endl;        cout << n << endl;        if(obstacleGrid[0][0] == 1) return 0;        else obstacleGrid[0][0] = 1;        bool flag = false;        int i = 1;        for(i = 1; i < n; i ++){            if(obstacleGrid[0][i] != 1)                obstacleGrid[0][i] = 1;            else{                flag = true;                break;            }        }                if(flag){            while(i < n){                obstacleGrid[0][i] = 0;                i ++;            }         }        flag = false;        for(i = 1; i < m; i ++){            if(obstacleGrid[i][0] != 1)                obstacleGrid[i][0] = 1;            else{                flag = true;                break;            }        }        if(flag){            while(i < m){                obstacleGrid[i][0] = 0;                i ++;            }         }        for(int i = 1; i < m; i ++){            for(int j = 1; j < n; j ++){                int temp = obstacleGrid[i][j - 1] + obstacleGrid[i - 1][j];                if(obstacleGrid[i][j] == 1) obstacleGrid[i][j] = 0;                else obstacleGrid[i][j] = temp;            }        }        return obstacleGrid[m - 1][n - 1];    }};