454C - Little Pony and Expected Maximum - CodeForces Solution

// Problem: C. Little Pony and Expected Maximum
// Contest: Codeforces - Codeforces Round 259 (Div. 2)
// URL: https://codeforces.com/contest/454/problem/C#
// Memory Limit: 256 MB
// Time Limit: 1000 ms
// 
// Powered by CP Editor (https://cpeditor.org)

#include <bits/stdc++.h>
#define rep1(i, j, n) for (int i(j); i <= n; ++i)
#define rep2(i, j, n) for (int i(j); i >= n; --i)
#define rep(i, n) for (int i(0); i < n; ++i)
#define per(i, n) for (int i(n - 1); ~i; --i)
#define i64 long long
#define ld long double
using namespace std;
signed main(void) {
	ios :: sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
	int n, m;
	cin >> m >> n;
	ld ans = 0;
	rep1(i, 1, m) {
		ans += i * (powl(1.0 * i / m, 1.0 * n) - powl((i - 1.0) / m, 1.0 * n));
	} cout << setprecision(12) << fixed << ans;
}