查找B字符串中出现的字符是否在A中全部出现

void check(string a, string b){map<char, int>A;bool flag = true;for (int i = 0; i < a.size(); i++)//构建字符串1的hash表{if (A.empty())A[a[i]] = 1;else{if (A.find(a[i]) != A.end())A[a[i]]++;elseA[a[i]] = 1;}}for (int i = 0; i < b.size(); i++){if (A.find(b[i]) != A.end()){if (A[b[i]] == 0){cout << "false";flag = false;break;}else{A[b[i]]--;}}else{cout << "false";flag = false;break;}}if (flag == true)cout << "true";}