LeetCode-Isomorphic Strings-解题报告

原题链接https://leetcode.com/problems/isomorphic-strings/

Given two strings s and t, determine if they are isomorphic.

Two strings are isomorphic if the characters in s can be replaced to gett.

All occurrences of a character must be replaced with another character while preserving the order of characters. No two characters may map to the same character but a character may map to itself.

For example,

Given

"egg"

,

"add"

, return true.

Given

"foo"

,

"bar"

, return false.

Given

"paper"

,

"title"

, return true.

Note:

You may assume both s and t have the same length.

解题报告:

一开始理解错，单纯的比较了一下两个串的前后字母是否相同，结果过了29个case，看了第30个case才知道是要做什么。

我们创建一个hash表，其实就是一个大小为256的数组，记录上一次字符出现的位置。将hash表初始化为-1.然后循环遍历字符串。

只需要判断上一次当前字母出现的位置 是否相同

class Solution {
public:
bool isIsomorphic(string s, string t) {
if (s.length() == 1)return true;
vector<int>sh(256, -1);
vector<int>th(256, -1);
for (int i = 0; i < s.length(); ++i)
{
if (sh[s[i]] != th[t[i]])return false;
sh[s[i]] = i;
th[t[i]] = i;
}
return true;
}
};