Added gas_station.py

data_structures/arrays/gas_station.py

@@ -0,0 +1,44 @@
+from typing import list
+
+class Solution:
+    def can_complete_circuit(self, gas: list[int], cost: list[int]) -> int:
+        # Step 1: Initialize variables
+        # total_gas will keep track of the total balance of gas - cost across all stations
+        # current_gas will track the gas balance for the current trip from the starting station
+        # start_station will track the potential starting point of the circuit
+        total_gas = 0
+        current_gas = 0
+        start_station = 0
+
+        # Step 2: Loop through each gas station
+        for i in range(len(gas)):
+            # Calculate the net gas gain/loss at the current station
+            total_gas += gas[i] - cost[i]
+            current_gas += gas[i] - cost[i]
+
+            # Step 3: If current_gas becomes negative, it means we cannot continue
+            # the journey from the current start_station, so we update the start_station
+            # to the next one and reset the current_gas to 0.
+            if current_gas < 0:
+                start_station = i + 1  # Move the starting station to the next one
+                current_gas = 0  # Reset the gas for the new start
+
+        # Step 4: Check if the total gas is enough to complete the circuit
+        # If total_gas is negative, it means the entire circuit cannot be completed
+        if total_gas < 0:
+            return -1
+        else:
+            # If total_gas is non-negative, return the start_station as the answer
+            return start_station
+
+# Example usage with hints:
+
+# Example 1:
+gas = [1, 2, 3, 4, 5]
+cost = [3, 4, 5, 1, 2]
+
+# Step-by-step hint:
+# 1. Start from station 3 (index 3), where the gas is 4 and the cost to the next station is 1.
+# 2. Keep tracking the current gas and total gas balance as you move through the stations.
+solution = Solution()
+print(solution.can_complete_circuit(gas, cost))  # Output: 3