LEET-T0134: Gas Station

#include <bits/stdc++.h>
using namespace std;

vector<int> gas, cost;

int canCompleteCircuit(vector<int> &gas, vector<int> &cost){
    int n = gas.size();
    int sumGas = 0;
    int sumCost = 0;
    int cur = 0;
    int mn = 0;
    int ans = 0;
    for(int i = 0; i < n; ++i){
        sumGas += gas[i];
        sumCost += cost[i];
        cur += gas[i] - cost[i];
        if(cur < mn){
            mn = cur;
            ans = (i + 1) % n;
        }
    }
    if(sumGas < sumCost){
        return -1;
    }
    return ans;
}

int main(){

    int n;
    scanf("%d", &n);
    for(int i = 1; i <= n; ++i){
        int x;
        scanf("%d", &x);
        gas.push_back(x);
    }
    for(int i = 1; i <= n; ++i){
        int x;
        scanf("%d", &x);
        cost.push_back(x);
    }
    cout << canCompleteCircuit(gas, cost);

    return 0;
}