HackerRank "Equal Stacks"

#include <vector>
#include <iostream>

using namespace std;


int main(){
    int n1;
    int n2;
    int n3;
    cin >> n1 >> n2 >> n3;
    long long l1 = 0, l2 = 0, l3 = 0;    
    vector<int> h1(n1);
    for(int h1_i = 0;h1_i < n1;h1_i++){
       cin >> h1[h1_i];
        l1 += h1[h1_i];
    }
    vector<int> h2(n2);
    for(int h2_i = 0;h2_i < n2;h2_i++){
       cin >> h2[h2_i];
        l2 += h2[h2_i];
    }
    vector<int> h3(n3);
    for(int h3_i = 0;h3_i < n3;h3_i++){
       cin >> h3[h3_i];
        l3 += h3[h3_i];
    }
    
    int i1 = 0, i2 = 0, i3 = 0;
    while(!(l1 == l2 && l2 == l3))
    {
        // which stack is highest now?
        int maxi = 1;
        int maxl = l1;        
        if(maxl < l2)
        {
            maxi = 2;         
            maxl = l2;
        }
        if(maxl < l3)
        {
            maxi = 3;
            maxl = l3;
        }
        
        //
        switch(maxi)
        {
        case 1:
            l1 -= h1[i1++];
            break;
        case 2:
            l2 -= h2[i2++];
            break;
        case 3:
            l3 -= h3[i3++];
            break;
        }
        
        if(!l1 || !l2 || !l3)
        {
            l1 = l2 = l3 = 0;
        }
    }
    cout << l1 << endl;
    return 0;
}