题解 | 【模板】前缀和

import sys

n, q = map(int, input().split())
a = list(map(int, input().split()))
a.insert(0, 0)
for i in range(1, n + 1):
    a[i] = a[i] + a[i - 1]

for i in range(q):
    x, y = map(int, input().split())
    print(a[y] - a[x - 1])