Leetcode 3694. Distinct Points Reachable After Substring Removal

• [Leetcode 3694. Distinct Points Reachable After Substring Removal](#Leetcode 3694. Distinct Points Reachable After Substring Removal)
  • [1. 解题思路](#1. 解题思路)
  • [2. 代码实现](#2. 代码实现)

• 题目链接：3694. Distinct Points Reachable After Substring Removal

1. 解题思路

这一题思路上就是一个滑动窗口的思路，我们首先计算出终点的位置，然后考察每一个连续长为 k k k的窗口的位移改变量，然后减去对应的改动量即可。

2. 代码实现

给出python代码实现如下：

class Solution:
    def distinctPoints(self, s: str, k: int) -> int:
        mapping = {"U": [0, 1], "D": [0, -1], "L": [-1, 0], "R": [1, 0]}
        cord = [0, 0]
        for ch in s:
            cord = [x+d for x, d in zip(cord, mapping[ch])]
        ans = set()
        delta = [0, 0]
        for i, ch in enumerate(s):
            delta = [x+d for x, d in zip(delta, mapping[ch])]
            if i-k >= 0:
                delta = [x-d for x, d in zip(delta, mapping[s[i-k]])]
            if i >= k-1:
                ans.add((cord[0]-delta[0], cord[1]-delta[1]))
        return len(ans)

提交代码评测得到：耗时1447ms，占用内存26.8MB。