LeetCode #205 - Isomorphic Strings-优快云博客

本文链接：https://blog.youkuaiyun.com/LawFile/article/details/81174661

本文介绍了一种通过哈希表来判断两个字符串是否为同构字符串的方法。利用两个哈希表记录每个字符出现的位置，遍历字符串并比较对应字符位置是否相同。

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题目描述：

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

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

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.

Example 1:

Input: s = "egg", t = "add"

Output: true

Example 2:

Input: s = "foo", t = "bar"

Output: false

Example 3:

Input: s = "paper", t = "title"

Output: true

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

判断两个字符串是否同构，定义两个哈希表，存储每个字母上一次出现的位置，遍历到当前字母时，比较两个字母分别在两个字符串上一次出现的位置是否一样，不一样就肯定不是同构。

class Solution {
public:
    bool isIsomorphic(string s, string t) {
        vector<int> hash1(256,-1);
        vector<int> hash2(256,-1);
        for(int i=0;i<s.size();i++)
        {
            if(hash1[s[i]]!=hash2[t[i]]) return false;
            else
            {
                hash1[s[i]]=i;
                hash2[t[i]]=i;
            }
        }
        return true;
    }
};