public static void main(String[] args){

int[] gas = new int[]{1,2,3,4,5};

int[] cost = new int[]{3,4,5,1,2};

int result = canCompleteCircuit(gas, cost);

System.out.println(result);

}

public static int canCompleteCircuit(int[] gas, int[] cost) {

int n = gas.length;

int result = -1;

int sum =0;

for(int a : gas) {

sum+= a;

}

for(int i = 0; i < n ; i++) {

if( cost[i] > gas[i]) continue;

result = util(i, gas, cost, sum,0,0);

if(result != -1) {

result = i ;

break;

}

}

return result;

}

public static int util(int now, int[] gas, int[] cost, int sum, int ga, int miles) {

/*

int longway = gas[now];

if(miles + longway + ga - cost[now] >= sum) return 1;

else if ( ga + longway - cost[now] >= 0){ // 如果能到下一个点

int index = now +1;

if(index >= gas.length) index = index - gas.length ;

return util(index, gas, cost, sum, ga +gas[now] - cost[now] , miles + cost[now]);

}

return -1;

}