CF140C New Year Snowmen

题目链接

这道题其实吧，水，我们教练说过，不要看标签，这只是CSP第一题的题目

思路嘛，priority_queue和贪心，就这样，很水

这是代码

还有，一定要在cf上交，不然……可以看一下提交记录，有几个人的代码回来了

Code

#include <cstdio>
#include <queue>
#include <algorithm>
using namespace std;
const int MAXN = 1e6 + 5;

inline int read(){
	int k = 0,f = 1;
	char ch = getchar();
	while(ch < '0' || ch > '9'){
		if (ch == '-'){
			f = -1;
		}
		ch = getchar();
	}
	while(ch >= '0' && ch <= '9'){
		k = k * 10 + ch - '0';
		ch = getchar();
	}
	return k * f;
}

inline void write(int x){
	if (x < 0){
		putchar('-');
		x = -x;
	}
	if (x > 9) write(x / 10);
	putchar(x % 10 + '0');
}

struct node{
	int cnt,num,id;
	node(){}
	node(int Cnt,int Num){
		cnt = Cnt,num = Num;
	}
	bool operator <(const node& a) const{
		return cnt < a.cnt;
	}
}a[MAXN];

priority_queue <node> q;
int cnt = 1;
int ans;

struct ball{
	int big,mid,sma;
}k[MAXN];

bool cmp(node x,node y){
	return x.num < y.num;
}

int main(){

	int n;
	n = read();

	for (int i = 1; i <= n ; i++) a[i].num = read();

	sort(a + 1,a + 1 + n,cmp);

	for (int i = 1; i <= n; i++){
		if (a[i].num != a[i + 1].num){
			q.push(node(cnt,a[i].num));
			cnt = 1;
		}
		else cnt++;
	}

	if (q.size() < 3){
		printf("0");
		return 0;
	}

	while(q.size() >= 2){
		node x = q.top();q.pop();
		node y = q.top();q.pop();
		node z = q.top();q.pop();
		x.cnt--,y.cnt--,z.cnt--;
		k[++ans].big = x.num;
		k[ans].mid = y.num;
		k[ans].sma = z.num;
		if (x.cnt)	q.push(node(x.cnt,x.num));
		if (y.cnt)	q.push(node(y.cnt,y.num));
		if (z.cnt)	q.push(node(z.cnt,z.num));
	}

	write(ans);
	putchar(10);

	for (int i = 1 ; i <= ans ; i++){
		int m[5];
		m[1] = k[i].big;
		m[2] = k[i].mid;
		m[3] = k[i].sma;
		sort(m + 1,m + 4);
		printf("%d %d %d\n",m[3],m[2],m[1]);
	}
	return 0;
}