[LeetCode] 63. Unique Paths II

轉自LeetCode

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.

<Solution>

Unique Path 的衍生題

這次增加的條件是，有些位置是無法到達的

那思路還是一樣，用 dynamic programming 的方式去解

解題想法如下

• 從位置 (0,0) 出發，如果遇到障礙物，就把該位置可到達步數清為0

• 如果沒遇到障礙物，就用 dp[i][j] = dp[i-1][j] + dp[i][j-1] 的概念去解

code 如下
c++

kotlin