2017ICPC/广西邀请赛1001（水）HDU6181

A Math Problem

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 817    Accepted Submission(s): 344

Problem Description

You are given a positive integer n, please count how many positive integers k satisfy kk≤n .

 

Input

There are no more than 50 test cases.

Each case only contains a positivse integer n in a line.

1≤n≤1018

 

Output

For each test case, output an integer indicates the number of positive integers k satisfy kk≤n in a line.

 

Sample Input

1 4

 

Sample Output

1 2

题意 

解析  数据会爆longlong 自己快速幂找到爆点 16爆了

#include <stdio.h>
#include <math.h>
#include <string.h>
#include <stdlib.h>
#include <iostream>
#include <sstream>
#include <algorithm>
#include <string>
#include <queue>
#include <vector>
using namespace std;
const int maxn= 200010;
const int inf = 0x3f3f3f3f;
typedef long long ll;
ll n;
ll pow1(ll a,ll b)
{
  ll r=1,base=a;
  while(b)
  {
    if(b&1) r*=base;
    base*=base;
    b>>=1;
  }
  return r;
}
int main(int argc, char const *argv[])
{
    while(scanf("%lld",&n)==1)
    {
        for(int i=15;i>=0;i--)
        {
            if(pow1(i,i)<=n)
            {
                cout<<i<<endl;
                break;
            }

        }
    }
    return 0;
}