A ← 整数列 # 从 1 开始
AC[0] ← 0

    
for i ← 1 to N-1:
    AC[i] ← AC[i-1] + A[i]

Q ← [l, r] 形式的问题数列

for q in Q:
    l ← q.l
    r ← q.r
    sum ← AC[r] - AC[l-1]