leetcode 63. Unique Paths II

class Solution {public:int uniquePathsWithObstacles(vector<vector<int>>& obstacleGrid){int a[101][101]{};int m = obstacleGrid.size();int n = obstacleGrid[0].size();for (int i = 1; i <= n; i++){if (obstacleGrid[0][i - 1] == 1){break;}a[1][i] = 1;}for (int i = 1; i <= m; i++){if (obstacleGrid[i - 1][0] == 1){break;}a[i][1] = 1;}for (int i = 2; i <= m; i++){for (int j = 2; j <= n; j++){if (obstacleGrid[i - 1][j - 1] == 0){a[i][j] = a[i - 1][j] + a[i][j - 1];}}}return a[m][n];}};