class Solution:
# @param A : tuple of integers
# @param B : tuple of integers
# @return an integer
def canCompleteCircuit(self, arr_a, arr_b):
total_a = len(arr_a)
available_fuel = 0
index = 0
arr_c = []
for i in range(total_a):
arr_c.append(arr_a[i] - arr_b[i])
for i in range(total_a):
available_fuel += arr_c[i]
while available_fuel < 0:
available_fuel -= arr_c[index]
index += 1
if index == i:
index = i + 1 # index += 1
available_fuel = 0
break
for i in range(index):
available_fuel += arr_c[i]
if available_fuel < 0:
index = -1
break
return indexDouble Pointer < O(n^2) Approach
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