2016 Multi-University Training Contest 3 1001 Sqrt Bo

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=5752

题目：

[align=left]Problem Description[/align]
Let's define the function
f(n)=⌊n−−√⌋.

Bo wanted to know the minimum number y
which satisfies fy(n)=1.

note:f1(n)=f(n),fy(n)=f(fy−1(n))

It is a pity that Bo can only use 1 unit of time to calculate this function each time.

And Bo is impatient, he cannot stand waiting for longer than 5 units of time.

So Bo wants to know if he can solve this problem in 5 units of time.

[align=left]Input[/align]
This problem has multi test cases(no more than
120).

Each test case contains a non-negative integer n(n<10100).

[align=left]Output[/align]
For each test case print a integer - the answer
y
or a string "TAT" - Bo can't solve this problem.

[align=left]Sample Input[/align]

233
233333333333333333333333333333333333333333333333333333333

手动判断一下。注意为0的情况。

#include <iostream>
#include<cstdio>
#include<cmath>
#include<cstring>
#define ll long long
using namespace std;

int main()
{
char s[1100];
while(~scanf("%s",s))
{
int len=strlen(s);
if(len==1&&s[0]=='0')
{
cout<<"TAT"<<endl;
continue;
}
if(len<=10)
{
ll num=0;
for(int i=0;i<len;i++)
{
num=num*10+(ll)(s[i]-'0');
}
if(num<2)  cout<<0<<endl;
else    if(num<4)  cout<<1<<endl;
else    if(num<16) cout<<2<<endl;
else    if(num<256)    cout<<3<<endl;
else    if(num<65536)   cout<<4<<endl;
else    if(num<4294967296) cout<<5<<endl;
else    cout<<"TAT"<<endl;
}
else    cout<<"TAT"<<endl;
}
}