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\n", cas, ans1, ans2); } return 0; }