Time: 722 ms (72.46%), Space: 19 MB (90.27%) - LeetHub

134-gas-station/134-gas-station.py

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+class Solution:
+    def canCompleteCircuit(self, gas: List[int], cost: List[int]) -> int:
+        
+        # Takes more gas to do a revolution than there is in the stations
+        if sum(cost) > sum(gas):
+            return -1
+        
+        n = len(gas)
+        startingIndex = 0
+        while startingIndex < n:
+            # Attempts to compelete a trip around the stations
+            currentGasLevel = 0
+            for i in range(n):
+                j = (i + startingIndex) % n
+                currentGasLevel += gas[j]   # Fill up at station j
+                
+                currentGasLevel -= cost[j]  # Cost to get to station (j+1)
+                
+                # Can the car the make it to the next station
+                if currentGasLevel < 0:
+                    startingIndex = j + 1
+                    break
+                    
+            else:
+                # Only executed if it made a full revolution
+                return startingIndex
+        
+        # Returns if there is no valid index
+        return -1