1031. Hello World for U (20)

//#include<string>
//#include <iomanip>
#include<vector>
#include <algorithm>
//#include<stack>
#include<set>
#include<queue>
#include<map>
//#include<unordered_set>
//#include<unordered_map>
//#include <sstream>
//#include "func.h"
//#include <list>
#include<stdio.h>
#include<iostream>
#include<string>
#include<memory.h>
#include<limits.h>
using namespace std;

int main(void)
{
string s;
cin >> s;
int n = s.size();
int n1 = 0, n2 = 0;
for (int i = 0; i < n; i++)
{//求出n1的最大值
n1 = i;
n2 = n + 2 - 2 * n1;
if (n2 < n1) break;
}
if (n2 < n1)
n1--;
n2 = n + 2 - 2 * n1;
string mid = "";
for (int i = 0; i < n2 - 2; i++)
mid += " ";

for (int i = 0; i < n1 - 1; i++)
{
cout << s[i] << mid << s[s.size() - 1 - i] << endl;
}
for (int i = n1 - 1; i < n1 - 1 + n2; i++)
{
cout << s[i];
}
cout << endl;
return 0;
}