Codeforces 453A Little Pony and Expected Maximum

题面在这里

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\[ \sum_{i=1}^m i\cdot \left[\left( \frac i m \right)^n - \left( \frac {i-1} m \right)^n\right] \]

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示例程序：

#include<cstdio>
#include<cmath>

int n,m;
int main(){
	scanf("%d%d",&m,&n);
	double ans=0;
	for (int i=1;i<=m;i++) ans+=i*(pow(1.0*i/m,n)-pow(1.0*(i-1)/m,n));
	printf("%.08f",ans);
	return 0;
}