isomorphic-strings.cpp

// 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.
//


class Solution {
public:
    bool isIsomorphic(string s, string t) {
        vector<int> s2t(256, -1);
        vector<int> t2s(256, -1);
        
        for (int i = 0; i < s.length(); ++i) {
            if (s2t[s[i]] != -1 && s2t[s[i]] != t[i]) {
                return false;
            }
            if (t2s[t[i]] != -1 && t2s[t[i]] != s[i]) {
                return false;
            }
            s2t[s[i]] = t[i];
            t2s[t[i]] = s[i];
        }
        return true;
    }
};