LeetCode63 Unique Paths II

题目：

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. （Medium）

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.

分析：

上一题的follow-up，加上了障碍物，思路一样，只是障碍物处dp[i][j] = 0;

代码：

 class Solution {
 public:
     int uniquePathsWithObstacles(vector<vector<int>>& obstacleGrid) {
         int m = obstacleGrid.size();
         int n = obstacleGrid[].size();
         int dp[m][n];
         memset(dp,,sizeof(dp));
         for (int i = ; i < n; ++i) {
             if (obstacleGrid[][i] == ) {
                 break;
             }
             dp[][i] = ;
         }
         for (int i = ; i < m; ++i) {
             if (obstacleGrid[i][] == ) {
                 break;
             }
             dp[i][] = ;
         }
         for (int i = ; i < m; ++i) {
             for (int j = ; j < n; ++j) {
                 if (obstacleGrid[i][j] == ) {
                     dp[i][j] = ;
                 }
                 else {
                     dp[i][j] = dp[i - ][j] + dp[i][j - ];
                 }
             }
         }
         return dp[m - ][n - ];
     }
 };

注：为什么这道题里dp[m][n] = {0}不能把二维数组初始化为0了......