自守数

自守数是指一个数的平方的尾数等于该数自身的自然数。例如：252 = 625，762 = 5776，93762 = 87909376。请求出n以内的自守数的个数

前者用字符串的思维进行处理

#include<iostream>#include<string>#include<stdlib.h>using namespace std;int main(){    int n, b;    int k = 0;    cin>>n;    for(int i = 0; i < n; i++){        int sum = i*i;        char schar[32];        char ichar[32];        itoa(sum, schar, 10);  // 将整型值转换为字符串        itoa(i, ichar,10);        string str(schar);    // 创建字符串str        string istr(ichar);        //cout<<"str = "<<str<<" ";        //cout<<"str.length() = "<<str.length()<<endl;        int len = istr.length();        if(str.substr(str.length() - len) == istr) {                //cout<<"i = "<<i<<endl;                k++;        }    }    cout<<k<<endl;}

<pre style="word-wrap: break-word; white-space: pre-wrap;">#include <iostream>using namespace std;int CalcAutomorphicNumbers( int n){int count=0;for(int i=0;i<=n;i++){int  sum=i*i;if (!(i/10))   //一位数{if(sum%10==i)count++;}else if (!(i/100))   //两位数{if(sum%100==i)count++;}else if (!(i/1000))   //三位数{if(sum%1000==i)count++;}else if (!(i/10000))   //四位数{if(sum%10000==i)count++;}}return count;}int main(){int num;cin>>num;cout<<CalcAutomorphicNumbers(num);}