Leftmost Digit
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
2
Hint
In 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.
题意:给一个整数N,要求输出N的N次方最左边的数;
分析:
令 N=X^X;
两边同时取对数 则 log10(N)=X*log10(X);
同时 X^X 也可以表示成 A*(10^k) 科学计数法表示
A的整数部分即是X^X的最高位
两式合并得 log10(A)+k=X*log10(X);
log10(A)小于1 即是右式的小数部分 k是右式的整数部分
此时只需通过右式算出k即可解得A
1 #include<cstdio> 2 #include<cstring> 3 #include<iostream> 4 #include<cmath> 5 using namespace std; 6 7 int main() 8 { 9 int T; 10 cin>>T; 11 while(T--) 12 { 13 double A,n; 14 long long k; 15 cin>>n; 16 A=n*log10(n); 17 A-=(long long)A; 18 k=pow(10.0,A); 19 cout<<k<<endl; 20 } 21 }