[Algorithm] 구간 합 구하기 4

[hwangJi-dev]

import sys
input = sys.stdin.readline

n, m = map(int, input().split())
arr = map(int, input().split())
prefixSum = [0]
sum = 0

for i in arr:
    sum += i
    prefixSum.append(sum)
    
for i in range(m):
	a, b = map(int, input().split())
	print((prefixSum[b]) - prefixSum[a - 1])