Portal
Title description
Give you a set of numbers, first determine an x, then find two numbers ai and aj on this set of numbers, add them to x, eliminate them, and then replace x with the larger value of the two numbers, and continue to the next round, Ask if you can delete all this set of numbers
analysis
First of all, in the first round, we must choose the largest one, then we enumerate what to choose from another number, and then continue to the next round.
Code
#include <iostream>
#include <cstdio>
#include <cmath>
#include <algorithm>
#include <map>
#include <queue>
#include <cstring>
#define debug(x) cout<<#x<<":"<<x<<endl;
#define _CRT_SECURE_NO_WARNINGS
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> PII;
const int INF = 0x3f3f3f3f;
const int N = 1e6 + 10;
int a[N];
bool st[N];
PII ans[N];
int n;
bool cmp(int x,int y){
return x > y;
}
int main(){
int t;
scanf("%d",&t);
while(t--){
map<int,int> M;
scanf("%d",&n);
for(int i = 1;i <= n * 2;i++) {
scanf("%d",&a[i]);
}
sort(a + 1,a + 1 + n * 2);
int res = 0;
int ppp;
for(int i = 1;i < 2 * n;i++){
for(int j = 1;j <= 2 * n;j++) st[j] = false;
res = 0;
int maxv = a[n * 2];
ans[++res] = {
a[i],a[2 * n]};
st[2 * n] = true;
st[i] = true;
ppp = a[i] + a[2 * n];
for(int j = 2 * n - 1;j;j--){
if(st[j]) continue;
int p = lower_bound(a + 1,a + 1 + 2 * n,maxv - a[j]) - a;
while(st[p] && p < 2 * n) p++;
// cout << maxv << ' ' << a[j] << ' ' << p << ' '<< a[p] << endl;
if(a[p] == maxv - a[j] && !st[p] && j != p){
st[j] = true;
st[p] = true;
ans[++res] = {
max(a[j],maxv - a[j]),min(a[j],maxv - a[j])};
maxv = max(a[j],maxv - a[j]);
}
}
// cout << res << endl;
if(res == n) break;
}
if(res == n) {
puts("YES");
printf("%d\n",ppp);
for(int i = 1;i <= n;i++) printf("%d %d\n",ans[i].first,ans[i].second);
}
else puts("NO");
}
return 0;
}
/**
* ┏┓ ┏┓+ +
* ┏┛┻━━━┛┻┓ + +
* ┃ ┃
* ┃ ━ ┃ ++ + + +
* ████━████+
* ◥██◤ ◥██◤ +
* ┃ ┻ ┃
* ┃ ┃ + +
* ┗━┓ ┏━┛
* ┃ ┃ + + + +Code is far away from
* ┃ ┃ + bug with the animal protecting
* ┃ ┗━━━┓ 神兽保佑,代码无bug
* ┃ ┣┓
* ┃ ┏┛
* ┗┓┓┏━┳┓┏┛ + + + +
* ┃┫┫ ┃┫┫
* ┗┻┛ ┗┻┛+ + + +
*/