Hdu 1060 Leftmost Digit
Leftmost DigitTime Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 15506 Accepted Submission(s): 6021Problem DescriptionGiven a po
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Leftmost Digit
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 15506 Accepted Submission(s): 6021
Problem Description
Given a positive integer N, you should output the leftmost digit of N^N.
Input
The input contains several test cases. The first line of the input is a single integer T which is the number of test cases. T test cases follow.
Each test case contains a single positive integer N(1<=N<=1,000,000,000).
Each test case contains a single positive integer N(1<=N<=1,000,000,000).
Output
For each test case, you should output the leftmost digit of N^N.
Sample Input
2 3 4
Sample Output
2 2HintIn the first case, 3 * 3 * 3 = 27, so the leftmost digit is 2. In the second case, 4 * 4 * 4 * 4 = 256, so the leftmost digit is 2.
Author
Ignatius.L
思路:这道题目是参考网络上大牛们写的,想法就是N*N=M,那么M=10^ ( N*log10 (N) ),【取一次对数再取10的对数次方】
又由于10^(a*b)【a为整数,b为小数】的最左一位数仅仅与b有关,===> 10^( c.d )[这c.d=a*b],也就是10^c*10^0.d次方,所以最高位仅 仅 受0.d的影响,所以有ans=ans-(int)ans , ans=N*log10(N), 再求( int ) 10^ans,就是答案了。膜拜数学大牛。。
AC代码如下:
#include <iostream>
#include <cstring>
#include <cmath>
using namespace std;
int main(){
double a,ans,tmp;
long long ttmp;
int t;
cin>>t;
while(t--){
cin>>a;
tmp=a*log10(a);
ttmp=(long long)tmp;
ans=tmp-ttmp;
cout<<(int)pow(10.0,ans)<<endl;
}
return 0;
}
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