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class Solution {
public:
    bool isIsomorphic(string s, string t) {
        char map_s[128] = { 0 };
        char map_t[128] = { 0 };
        int len = s.size();
        for(int i = 0; i < len; ++i){
            if(map_s[s[i]] != map_t[t[i]]) return false;
            map_s[s[i]] = i+1;
            map_t[t[i]] = i+1;
        }
        return true;
    }
};