Approximate

import sys

lines = sys.stdin.readlines()

def asints(s):
	return [int(x.strip()) for x in s.split()]

n, q = asints(lines[0])
sequence = asints(lines[1])

for i in range(2, q + 2):
	low, high = asints(lines[i])
	subs = sequence[low-1:high]
	avg = sum(subs) *1.0 / len(subs)
	errs = [(x*1.0-avg)**2 for x in subs]
	print sum(errs) / len(errs)
	

Test 1

Verdict: TIME LIMIT EXCEEDED