题解 | #Hello World for U#

注意区分str.size()是否是3的倍数

#include <iostream>
using namespace std;

int main(){
	string str;
	while (cin >> str){
		int temp;
		if (str.size()%3 == 0) //3的倍数 则计算完n1后要减1
			temp = str.size()/3-1;//n1 n3
		else temp = str.size()/3; //否则不用减
		int p = str.size()-2*temp-2;//空格
        
		int i,j;
	  //输出n1 N3
		for (i = 0,j = str.size()-1; i<temp;i++,j--){
			cout << str[i];
			for (int k =1;k <= p;k++) cout<<" ";
			cout << str[j]<<endl;
		}
	  
	  //输出n2
		for (; i <=j;i++){//n2
			cout <<str[i];
		}
        cout<<endl;
	}
}