array if alternate +ve and -ve

#include<iostream>
#include<cstdio>
#include<vector>
using namespace std;
int main(){
    int t; scanf("%d", &t);
    while(t--){
        int n; scanf("%d", &n);
        vector<int> positive;
        vector<int> negative;
        for(int i = 0; i < n; i++){
            int k; scanf("%d", &k);
            if(k < 0){
                negative.push_back(k);
            }
            else positive.push_back(k);
        }
        int count = 0;
        auto a = positive.begin();
        auto b = negative.begin();
        while((a != positive.end()) && (b != negative.end())){
            count++;
            if(count % 2){
                printf("%d ", *a++);
                //positive.erase(positive.begin());
            }
            else {
                printf("%d ", *b++);
               // negative.erase(negative.begin());
            }
        }
        if(a == positive.end()){
            while(b != negative.end()){
                printf("%d ", *b++);
                //negative.erase(negative.begin());
            }
        }
        else{
            while(a != positive.end()){
                printf("%d ", *a++);
                //positive.erase(positive.begin());
            }
        }
        printf("\n");
    }
}