leetcode---Unique Paths II---动规

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.

class Solution {
public:
int uniquePathsWithObstacles(vector<vector<int>>& obstacleGrid)
{
int row = obstacleGrid.size();
int col = obstacleGrid[0].size();
int dp[101][101];
memset(dp, 0, sizeof(dp));
dp[0][0] = obstacleGrid[0][0] == 0? 1 : 0;
for(int i=1; i<row; i++)
if(obstacleGrid[i][0] == 0)
dp[i][0] = dp[i-1][0];
for(int i=1; i<col; i++)
if(obstacleGrid[0][i] == 0)
dp[0][i] = dp[0][i-1];
for(int i=1; i<row; i++)
for(int j=1; j<col; j++)
dp[i][j] = obstacleGrid[i][j]==0? dp[i-1][j] + dp[i][j-1] : 0;
return dp[row-1][col-1];
}
};