手写priority_queue

（远古代码，真正的pq不是这样的

#include <iostream>
#include <cstdio>
#include <algorithm>
using namespace std;
int a[100005];
int n;
int l = 1, r = 1;
void push(int x){//插入
    int i = r++;
    while(i > l){
        if(a[i] > x){
            swap(a[i], a[i + 1]);
            i--;
    	}else break;
    }a[++i] = x;
}void pop(){
	l++;
}int size(){
	return r - l + 1;
}int back(){
	return a[l];
}
int main(){
	cin >> n;
	for(int i = 1; i <= n; i++){
		cin >> a[i];
	}r = n;
	sort(a + 1, a + r + 1);
	int ct = 0;
	while(size() != 1){
		int _1 = back();
		pop();
		int _2 = back();
		pop();
		ct += _1 + _2;
		push(_1 + _2);
	}cout << ct;

	return 0;
}

时间复杂度：$O(n^2)$