134. 加油站

class Solution {
    public int canCompleteCircuit(int[] gas, int[] cost) {
        int gasing,i,j,k;
        for(i = 0; i < gas.length;i = i + k + 1){
            gasing = gas[i];
            j=i;
            for(k=0; k < gas.length;k++){
                
                if(gasing - cost[j] < 0){
                    break;
                }
                
                gasing = gasing + gas[(j + 1) % gas.length] - cost[j ];
                j = ++j % gas.length;
            }
            if(k == gas.length){
                    return i;
                }
        }
        return -1;
    }
}