LeetCode 刷题【134. 加油站】

134. 加油站

自己做（超时）

class Solution {
    public int canCompleteCircuit(int[] gas, int[] cost) {
        int res = -1;

        for(int i = 0; i < gas.length; i++){
            int sum = 0;
            //顺时针走
            for(int j = 0; j < gas.length; j++){
                int index = (i + j) % gas.length;
                sum += gas[index] - cost[index];
                if(sum < 0){                             //走不到
                    sum = 0;
                    break;
                }

                if(j == gas.length - 1)                //走通了
                    res = i;
            }
            
            if(res != -1)                               //如果已经走通就没必要再走了
                break;
        }

        return res;

    }
}

看题解

官方题解

class Solution {
    public int canCompleteCircuit(int[] gas, int[] cost) {
        int n = gas.length;
        int i = 0;
        while (i < n) {
            int sumOfGas = 0, sumOfCost = 0;
            int cnt = 0;
            while (cnt < n) {
                int j = (i + cnt) % n;
                sumOfGas += gas[j];
                sumOfCost += cost[j];
                if (sumOfCost > sumOfGas) {
                    break;
                }
                cnt++;
            }
            if (cnt == n) {
                return i;
            } else {
                i = i + cnt + 1;
            }
        }
        return -1;
    }
}