HDU 2114 Calculate S(n)
http://acm.hdu.edu.cn/showproblem.php?pid=2114
Problem Description
Calculate S(n).
S(n)=13+23 +33 +......+n3 .
S(n)=13+23 +33 +......+n3 .
Input
Each line will contain one integer N(1 < n < 1000000000). Process to end of file.
Output
For each case, output the last four dights of S(N) in one line.
Sample Input
1
2
Sample Output
0001
0009
时间复杂度:$O(n)$
代码:
#include <bits/stdc++.h> using namespace std; long long a[10010]; long long A(long long x) { return x * x % 10000 * x % 10000; } int main() { long long n, S; for(int i = 1; i <= 10000; i ++) { a[i] = (a[i-1] + A(i))%10000; } while(~scanf("%lld", &n)) { printf("%04lld\n", a[ n % 10000]); } return 0; }