Gas Station@leetcode

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There are N gas stations along a circular route, where the amount of gas at station i is gas[i].

You have a car with an unlimited gas tank and it costs cost[i] of gas to travel from station i to its next station (i+1). You begin the journey with an empty tank at one of the gas stations.

Return the starting gas station's index if you can travel around the circuit once, otherwise return -1.

Note:
The solution is guaranteed to be unique.

题没什么难的，就是要注意这是一个circular route, i后面连接的是0，所以index需要处理，而走了多远要用一个额外的变量记录。

刚开始一直time limit exceed，因为我是一个一个station作为start去尝试，后来想其实没必要，因为假如一旦有一个route走不通，我们重新开始的station应该是我们中断的下一个，因为前面的任何一个开始都不会可以，可以证明出来，不细说了，自己想想就可以知道。