can anyone tell me whats wrong with this logic ,it passes 9 test cases but fails in others by saying doesnt execute within limits

def arrayManipulation(n, q):
arr = []
for i in range(n):
    arr.append(0)
for i in range(m):
    a = q[i][0]
    b = q[i][1]
    c = q[i][2]
    for j in range(a - 1, b):
        arr[j] = arr[j] + c
print(max(arr))