Isomorphic Strings

Two strings are isomorphic when characters in string S can replace characters in string T to make them identical. The mapping rule: each character maps to exactly one other character. Different source characters cannot map to the same target character.

class Solution {
public:
    bool isIsomorphic(string s, string t) {
        vector<char> m(257, '#');
        vector<bool> count(257, false);
        
        // Build the mapping
        for(int i=0;i<s.size();++i) {
            int idx = s[i];
            if(m[idx] == '#') {
                m[idx] = t[i];
            } else if (m[idx]!=t[i]) {
                return false;
            }
        }
        
        // Check if any target character has multiple sources
        for(int i=0;i<m.size();++i) {
            if (m[i] == '#') continue;
            int idx = m[i];
            if (count[idx] == false) {
                count[idx] = true;
            } else {
                return false;
            }
        }
        return true;
    }
};

#string

Integer to Roman Conversion Largest Component Size by Common Factor