「杂题乱刷2」CF827B

合集 - 贪心(58)

1.「杂题乱刷」CF1904B2023-12-102.「杂题乱刷」CF1620E2023-12-143.「杂题乱刷」CF978G2023-12-164.「杂题乱刷」洛谷P92532023-11-235.「杂题乱刷」CF624B2023-11-236.「杂题乱刷」CF1221B2023-11-237.「杂题乱刷」CF1585B2023-11-238.「杂题乱刷」CF468A2023-11-239.「杂题乱刷」洛谷P95152023-11-2310.「杂题乱刷」CF283A2023-11-2311.「杂题乱刷」洛谷P95332023-12-1812.「杂题乱刷」CF1914E1 & CF1914E22023-12-2013.「杂题乱刷」AT_abc280_d2023-12-2214.「杂题乱刷」CF1916C2023-12-3115.「杂题乱刷」AT_arc041_b2024-01-0316.【待补题解】AT_arc146_a2024-01-0317.「杂题乱刷」AT_abc337_e2024-01-2118.「杂题乱刷」AT_abc308_f2024-01-2619.「杂题乱刷」ZhengRui 54. 【17 普及 13】幻想嘉年华2024-01-2720.「杂题乱刷」CF1925C & CF1924A2024-01-3121.「杂题乱刷」CF1927D2024-02-0722.「杂题乱刷」洛谷 P101552024-02-1323.「杂题乱刷」洛谷 P17122024-02-1724.「杂题乱刷」洛谷 P88662024-02-2525.「杂题乱刷」CF1937C & CF1936A2024-03-0126.「杂题乱刷」CF1934D22024-03-0327.「杂题乱刷」洛谷 P48012024-03-0328.「杂题乱刷」ZhengRui 611 【19寒假普转提】树的权2024-03-0629.「杂题乱刷」ZhengRui 281 汪初雪与高流星2024-03-1230.「杂题乱刷」at_abc092_d & AT_arc093_b2024-04-0131.「杂题乱刷」CF74E2024-04-0132.「杂题乱刷」AT_abc279_e2024-04-2333.「杂题乱刷」AT_abc096_d2024-05-0534.「杂题乱刷」CF1973D2024-05-2035.「杂题乱刷」CF1650D2024-05-2336.「杂题乱刷」CF1650E2024-05-2337.「杂题乱刷」CF1977B2024-05-2838.「杂题乱刷」CF1977C2024-05-2839.「杂题乱刷」CF460C2024-05-3040.「杂题乱刷」P82792024-05-3141.「杂题乱刷」AT_abc160_e2024-06-0742.「杂题乱刷」P105122024-06-1043.「杂题乱刷」AT_abc358_g2024-06-1644.「杂题乱刷」 AT_abc123_d2024-06-2345.「杂题乱刷」P7840 & AT_abc359_f2024-06-2346.「杂题乱刷」CF1987C2024-07-0147.「杂题乱刷」P106782024-07-0248.「杂题乱刷2」CF1702F2024-07-0349.「杂题乱刷2」CF402D Upgrading Array2024-07-0550.「杂题乱刷2」CF1506E Restoring the Permutation2024-07-1451.「杂题乱刷2」CF727D2024-07-1452.「杂题乱刷2」CF1615C Menorah2024-07-1553.「杂题乱刷2」CF1889A Qingshan Loves Strings 22024-07-2654.「杂题乱刷2」CF1527B22024-09-1755.「杂题乱刷2」CF1108E22024-09-17

56.「杂题乱刷2」CF827B2024-10-03

57.「杂题乱刷2」CF1227D22024-10-0458.「杂题乱刷2」CF2066B02-13

收起

题目链接

CF827B

解题思路

假设树以 $1$ 为根，考虑先将 $k$ 个深度为 $1$ 的节点，然后我们就可以将剩余的节点挂在目前的叶子节点上，但是如果一个叶子节点挂了 $2$ 个叶子节点的话，那么这样叶子节点数目你一定不能使叶子节点减少，因此一个叶子节点最多只能往下挂一个节点，因此你直接用优先队列维护即可。

时间复杂度 $O(n\log n)$。

参考代码

点击查看代码

#include<bits/stdc++.h>
using namespace std;
//#define map unordered_map
#define re register
#define ll long long
#define forl(i,a,b) for(re ll i=a;i<=b;i++)
#define forr(i,a,b) for(re ll i=a;i>=b;i--)
#define forll(i,a,b,c) for(re ll i=a;i<=b;i+=c)
#define forrr(i,a,b,c) for(re ll i=a;i>=b;i-=c)
#define pii pair<ll,ll>
#define mid ((l+r)>>1)
#define lowbit(x) (x&-x)
#define pb push_back
#define IOS ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
#define endl '\n'
#define QwQ return 0;
#define db long double
#define ull unsigned long long
#define lcm(x,y) (1ll*(x)/__gcd(x,y)*(y))
#define Sum(x,y) (1ll*((x)+(y))*((y)-(x)+1)/2)
#define x first
#define y second
#define aty cout<<"Yes\n";
#define atn cout<<"No\n";
#define cfy cout<<"YES\n";
#define cfn cout<<"NO\n";
#define xxy cout<<"yes\n";
#define xxn cout<<"no\n";
#define printcf(x) x?cout<<"YES\n":cout<<"NO\n";
#define printat(x) x?cout<<"Yes\n":cout<<"No\n";
#define printxx(x) x?cout<<"yes\n":cout<<"no\n";
#define maxqueue priority_queue<ll>
#define minqueue priority_queue<pii,vector<pii>,greater<pii>>
#define bug cout<<"---------------------------------------\n";
//ll pw(ll x,ll y,ll mod){if(y==0)return 1;if(x==0)return 0;ll an=1,tmp=x;while(y){if(y&1)an=(an*tmp)%mod;tmp=(tmp*tmp)%mod;y>>=1;}return an;}
template<typename T1,typename T2>bool Max(T1&x,T2 y){if(y>x)return x=y,1;return 0;}
template<typename T1,typename T2>bool Min(T1&x,T2 y){if(y<x)return x=y,1;return 0;}
ll _t_;
void _clear(){}
ll n,m;
minqueue q;
vector<pii>ans;
ll a[200010];
ll k;
void solve()
{
    _clear();
	cin>>n>>m;
	if(m==2)
	{
		cout<<n-1<<endl;
		forl(i,1,n-1)
			cout<<i<<' '<<i+1<<endl;
		return ;
	}
	forl(i,2,m+1)
		q.push({1,i}),ans.pb({1,i}),a[++k]=1;
	forl(i,m+2,n)
	{
		pii now=q.top();
		q.pop();
		ans.pb({now.y,i});
		a[++k]=now.x+1;
		q.push({now.x+1,i});
	}
	sort(a+1,a+1+k);
	cout<<a[k]+a[k-1]<<endl;
	for(auto i:ans)
		cout<<i.x<<' '<<i.y<<endl;
}
int main()
{
//    freopen("tst.txt","r",stdin);
//    freopen("sans.txt","w",stdout);
    IOS;
    _t_=1;
  //  cin>>_t_;
    while(_t_--)
        solve();
    QwQ;
}