codeforces672 A (数字转换成字符串)

把数字转换成字符串，一种写法to_string但编译器不一定支持。

#include <cstdio>#include <cstring>#include <algorithm>#include <iostream>#include <string>#include <vector>#include <stack>#include <bitset>#include <cstdlib>#include <cmath>#include <set>#include <list>#include <deque>#include <map>#include <queue>using namespace std;typedef long long ll;int main (){    int i;    string s;    for(i=1;i<=1000;i++){        if (s.size() > 1000) break;        int num = i;        s+= to_string (num);    }    int n;    cin >> n;    cout << s[n-1];    return 0;}

另外一种写法


include <bits/stdc++.h>
using namespace std;
template<typename T> string toString(const T& t){
ostringstream oss; //创建一个格式化输出流
oss<<t; //把值传递如流中
return oss.str();
}
int main()
{
string str;
int i=1;
string s;
while(1)
{
s=toString(i);
str=str+s;
if(str.length()>=1000)
break;
i++;
}
int n;
scanf("%d",&n);
cout<<str[n-1]<<endl;
return 0;
}