Gas Station
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.
这题理解题意之后很简单,即要保证gas - cost 的和一直是正的就可以了。 但是要注意这是一个circular。
1 public class Solution { 2 public int canCompleteCircuit(int[] gas, int[] cost) { 3 // Note: The Solution object is instantiated only once and is reused by each test case. 4 if(gas.length == 0) return -1; 5 for(int i = 0; i < gas.length; i ++){ 6 gas[i] = gas[i] - cost[i]; 7 } 8 for(int i = 0; i < gas.length; i ++){ 9 int sum = 0; 10 boolean sig = true; 11 for(int j = i; j < gas.length; j ++){ 12 sum += gas[j]; 13 if(sum < 0){ 14 sig = false; 15 break; 16 } 17 } 18 for(int j = 0; j < i; j ++){ 19 sum += gas[j]; 20 if(sum < 0){ 21 sig = false; 22 break; 23 } 24 } 25 if(sig == true)return i; 26 } 27 return -1; 28 } 29 }
posted on 2013-10-18 07:20 Step-BY-Step 阅读(213) 评论(0) 编辑 收藏 举报