我的 #include<stdio.h> #include<iostream> #include<string> using namespace std; int main(){ int T; cin >> T; while(T--){ long long K; cin >> K; string ret; K = K-1; long long temp = 1; while(K>0){ temp = temp*2; if(K%temp<temp/2) ret = '4'+ret; else ret = '7'+ret; K = K-temp; } cout << ret <<endl; } return 0; }