题解 | 添加逗号
添加逗号
https://www.nowcoder.com/practice/f51c317e745649c0900996fd3f683aed?tpId=383&tqId=144140&channelPut=tracker1
#include <iostream>
#include <string>
using namespace std;
using ll = long long;
int main()
{
string s;
cin>>s;
ll len=s.length();
if(len<=3){//先特殊情况特殊判断一下
cout<<s;
return 0;
}
for(int i = len-3;i>0;i-=3){//倒着插入 ，避免索引位置变化的问题
s.insert(i,",");
}
cout<<s;
return 0;
}
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