Leading and Trailing

You are given two integers: n and k, your task is to find the most significant three digits, and least significant three digits of nk.

Input

Input starts with an integer T (≤ 1000), denoting the number of test cases.

Each case starts with a line containing two integers: n (2 ≤ n < 231) and k (1 ≤ k ≤ 107).

Output

For each case, print the case number and the three leading digits (most significant) and three trailing digits (least significant). You can assume that the input is given such that nk contains at least six digits.

Sample Input

5

123456 1

123456 2

2 31

2 32

29 8751919

Sample Output

Case 1: 123 456

Case 2: 152 936

Case 3: 214 648

Case 4: 429 296

Case 5: 665 669

后三位数字可以通过快速幂取模运算来获得,前三位数字可以通过对数的小数部分来获得!

#include<iostream>
#include<cstdio>
#include<cmath>
#include<cstring>
#include<sstream>
#include<algorithm>
#include<queue>
#include<vector>
#include<cmath>
#include<map>
#include<stack>
#include<set>
#include<fstream>
#include<memory>
#include<list>
#include<string>
using namespace std;
typedef long long LL;
typedef unsigned long long ULL;
#define MAXN  1000010
#define LLL 1000000000
#define INF 1000000009
LL Pow(LL x,LL k)
{
    LL ret = 1;
    while (k)
    {
        if (k & 1!=0)
            ret = (ret*x)%1000;
        x = x*x;
        x %= 1000;
        k /= 2;
    }
    return ret;
}
int main()
{
    int T;
    LL n, k;
    cin >> T;
    for (int cas = 1; cas <= T; cas++)
    {
        scanf("%lld%lld", &n, &k);
        LL tmp = n % 1000;
        LL ans2 = Pow(tmp, k)%1000,ans1;
        double num = k*log10(n*1.0);
        num -= LL(num);
        ans1 = LL(pow(10, num) * 100);
        printf("Case %d: %lld %03lld
", cas, ans1, ans2);
    }
    return 0;
}
原文地址:https://www.cnblogs.com/joeylee97/p/6831310.html