【LeetCode】C# 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.

延续上题Unique Path。在mn矩阵的举出上加上一些为1的元素。当格子为一，则线路不通。

思路：和Unique Path完全相同，在基础上加上对obstacleGrid[,]值得判断而已。

public class Solution {
public int UniquePathsWithObstacles(int[,] obstacleGrid) {
int m = obstacleGrid.GetLength(0);
int n = obstacleGrid.Length / m;
int[,] res = new int[m, n];
int c=-1;
if (m <= 1 || n <= 1){
while(++c<m)
if(obstacleGrid[c,0] == 1) return 0;
c=-1;
while(++c<n)
if(obstacleGrid[0,c] == 1) return 0;
return 1;

};
int sign = 1;
for (int i = 0; i < n; i++)
{
if (obstacleGrid[0, i] == 1)
{
sign = 0;
res[0, i] = sign;
}
else res[0, i] = sign;
}
sign = 1;
for (int i = 0; i < m; i++)
{
if (obstacleGrid[i, 0] == 1)
{
sign = 0;
res[i, 0] = sign;
}
else res[i, 0] = sign;
}
//res[1, 0] = 1;
for (int i = 1; i < n; i++)
{
for (int j = 1; j < m; j++)
{
if (obstacleGrid[j, i] != 1)
res[j, i] = res[j - 1, i] + res[j, i - 1];
}
}
return res[m - 1, n - 1];
}
}