1031 Hello World for U （20 分）

題目意思就是給你一串字串，給出U型圖。
方法：求出字串長度 n , 然後得 m = n+2
          然後再得到 n1=n3=m/3，同時n2 = m - n1*2；
我寫的程式碼中求出的n2是比上面的n2少2.

#include <bits/stdc++.h> 
using namespace std;
int main() {
	//freopen("datain.txt","r",stdin); 
	string s;
 

	cin>>s;
	int n = s.length();
	//cout<<n<<endl;
	int n1 = (n+2)/3;
	int n2 = n-n1*2;
	//cout<<n1<<" "<<n2<<endl;
	string s1 = s.substr(0,n1);//n1字串
	string s2 = s.substr(n1,n2);//n2字串
	string s3 = s.substr(n1+n2);//n3字串
	//cout<<s1<<" "<<s2<<" "<<s3<<endl;
 

	for (int i = 0; i < n1; i++) {
		cout<<s1[i];
		for (int j = 0; j < n2; j++) {
			if (i != n1-1) //中間空格 
				cout<<" ";
			else //最後一行
				cout<<s2[j];
		}
		cout<<s3[n1-i-1]<<endl;
	}
	return 0;
}