Codeforces 362D Fools and Foolproof Roads Constructor

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Question:

An undirected graph with m edges given at n points needs to add p edges to the vertex so that the number of connected components at the end of the graph is q.

Whether the problem is feasible or not.

YES can be output in rows, and the added p edge is output.

Set ..

#include<stdio.h>#include<iostream>#include<string.h>#include<algorithm>#include<vector>#include<set>using namespace std;#define N 123456#define ll __int64ll n,m,p,q;struct Edge{ll from, to, dis;}edge[N*2];ll edgenum;void add(ll u,ll v,ll dis){Edge E={u,v,dis};edge[edgenum++] = E;}ll f[N];ll find(ll x){return x==f[x]?x:f[x]=find(f[x]);}void Union(ll x,ll y){ll fx = find(x), fy = find(y);if(fx==fy)return ;if(fx<fy)swap(fx,fy);f[fx]=fy;}set<ll>myset;set<ll>::iterator pp;ll siz[N];vector<int>L,R;struct node{ll fa, val;bool operator<(const node&x)const{if(x.val==val)return x.fa<fa;return x.val>val;}node(ll x=0,ll y = 0):fa(x),val(y){}};set<node>hehe;set<node>::iterator dd;void init(){hehe.clear();L.clear(); R.clear();memset(siz, 0, sizeof siz);myset.clear();for(ll i = 1; i <= n; i++)f[i]=i;edgenum = 0;}void go(){dd = hehe.begin();node x = *dd;hehe.erase(dd);dd = hehe.begin();node y = *dd;hehe.erase(dd);Union(x.fa,y.fa);ll now = min((ll)1000000000, x.val+y.val+1);node z = node(find(x.fa),x.val+y.val+now);hehe.insert(z);L.push_back(x.fa); R.push_back(y.fa);add(x.fa,y.fa,1);}int main(){ll i, j, u, v, d;while(~scanf("%I64d %I64d %I64d %I64d",&n,&m,&p,&q)){init();while(m--){scanf("%I64d %I64d %I64d",&u,&v,&d);add(u,v,d);Union(u,v);}for(i = 1; i <= n; i++)find(i);for(i = 1; i <= n; i++)myset.insert(f[i]);for(i = 0; i < edgenum; i++){siz[f[edge[i].from]]+=edge[i].dis;}if(myset.size()<q){puts("NO");continue;}if(myset.size()==q){if(p && edgenum==0)puts("NO");else {puts("YES");while(p--){cout<<edge[0].from<<" "<<edge[0].to<<endl;}}continue;}ll ned = myset.size()-q;if(ned>p){puts("NO");continue;}p-=ned;for(pp=myset.begin(); pp!=myset.end(); pp++)hehe.insert(node(*pp,siz[*pp]));while(ned--)go();puts("YES");for(i = 0; i < L.size(); i++)cout<<L[i]<<" "<<R[i]<<endl;while(p--)cout<<edge[0].from<<" "<<edge[0].to<<endl;}return 0;}