class Solution {
public:
    string decodeMessage(string key, string message) {
        int arr[26]{}, n = 0;
        //memset(arr, -1, sizeof(arr));
        fill(arr, arr + 26, -1);
        for (char& c : key) {
            if (n >= 26) break;
            if (islower(c) && arr[c - 'a'] == -1) {
                arr[c - 'a'] = n;
                n++;
            }
        }
        string ans = "";
        for (char& c : message) {
            //if (islower(c)) ans += (char)arr[c - 'a']; 修改前
            if (islower(c)) ans += arr[c - 'a'] + 'a';  // 修改后
            else ans += c;
        }
        return ans;
    }
};