Submission #691968

---

Source Code Expand

#include <bits/stdc++.h>
using namespace std;
typedef signed long long ll;

#undef _P
#define _P(...) (void)printf(__VA_ARGS__)
#define FOR(x,to) for(x=0;x<(to);x++)
#define FORR(x,arr) for(auto& x:arr)
#define ITR(x,c) for(__typeof(c.begin()) x=c.begin();x!=c.end();x++)
#define ALL(a) (a.begin()),(a.end())
#define ZERO(a) memset(a,0,sizeof(a))
#define MINUS(a) memset(a,0xff,sizeof(a))
//-------------------------------------------------------

int N;
int W[201010];
int T[201010];
/*
int S[101010];
ll dp[3030][3030];
int sp[3030][3030];
*/

int lef[201010],rig[201010];
int depth[201010];
set<pair<int,int>> SS;
set<pair<int,int>> R[201010];
/*
void slow(){
	int i,j,k,l,r,x,y; string s;
	FOR(i,N) dp[i][i]=0,sp[i][i]=i;
	FOR(i,N-1) dp[i][i+1]=(W[i]+W[i+1]),sp[i][i+1]=i;
	
	for(i=2;i<=N-1;i++) {
		for(x=0;x+i<N;x++) {
			dp[x][x+i]=1LL<<60;
			for(y=sp[x][x+i-1];y<=sp[x+1][x+i];y++) {
				if(dp[x][y]+dp[y+1][x+i]<dp[x][x+i]) {
					dp[x][x+i]=dp[x][y]+dp[y+1][x+i];
					sp[x][x+i]=y;
				}
			}
			dp[x][x+i]+=S[x+i+1]-S[x];
		}
	}
	cout<<dp[0][N-1]<<endl;
}
*/

void solve() {
	int i,j,k,l,r,x,y; string s;
	
	cin>>N;
	FOR(i,N) cin>>W[i];
	
	//if(N<=3000) return slow();
	FOR(i,N) lef[i]=max(i-1,0), rig[i]=min(N-1,i+1);
	
	FOR(i,N-1) {
		R[i].insert({W[i],i});
		R[i].insert({W[i+1],i+1});
		T[i]=W[i]+W[i+1];
		SS.insert({T[i],i});
	}
	
	int nex=N;
	while(SS.size()) {
		/*
		FORR(r,SS) _P("%d:%d ",r.first,r.second);
		_P("\n");
		FOR(i,N-1) if(rig[i]>=0) _P("%d:%d:%d(%d) ",lef[i],i,rig[i],R[i].size());
		_P("\n");
		*/
		auto r=*SS.begin();
		SS.erase(SS.begin());
		x=r.second;
		/*
		FORR(rr,R[x]) _P("<%d:%d>",rr.first,rr.second);
		_P("x=%d %d\n",x,R[x].size());
		*/
		if(R[x].size()==1) {
			break;
		}
		auto rx=R[x].begin()->second;
		R[x].erase(R[x].begin());
		auto ry=R[x].begin()->second;
		R[x].erase(R[x].begin());
		/*
		FORR(rr,R[x]) _P("<%d:%d>",rr.first,rr.second);
		_P("x=%d %d\n",x,R[x].size());
		
		_P("%d-%d %d %d -> %d\n",x,rig[x],rx.second,ry.second,nex);
		*/
		lef[nex]=rx;
		rig[nex]=ry;
		W[nex]=W[rx]+W[ry];
		R[x].insert({W[nex],nex});
		
		if((rx==x || ry==x) && x){
			// merge lef
			//_P("lef\n");
			y=lef[x];
			rig[y]=rig[x];
			lef[rig[x]]=y;
			SS.erase({T[y],y});
			R[y].erase({W[x],x});
			if(R[y].size()<R[x].size()) swap(R[x],R[y]);
			FORR(r,R[x]) R[y].insert(r);
			R[x].clear();
			rig[x]=-1;
			x=y;
		}
		if((rx==rig[x] || ry==rig[x]) && rig[x]<N-1){
			//_P("ri\n");
			y=rig[x];
			lef[rig[y]]=x;
			rig[x]=rig[y];
			SS.erase({T[y],y});
			R[y].erase({W[y],y});
			if(R[y].size()>R[x].size()) swap(R[x],R[y]);
			FORR(r,R[y]) R[x].insert(r);
			R[y].clear();
			rig[y]=-1;
		}
		
		auto it=R[x].begin();
		T[x]=it->first;
		it++;
		T[x]+=it->first;
		SS.insert({T[x],x});
		nex++;
	}
	
	for(i=nex-1;i>=N;i--) depth[lef[i]]=depth[rig[i]]=depth[i]+1;
	
	
	ll ret=0;
	//FOR(i,N) _P("%d:%d:%d ",i,depth[i],W[i]);
	FOR(i,N) ret+=depth[i]*W[i];
	cout<<ret<<endl;
	
	
}


int main(int argc,char** argv){
	string s;int i;
	if(argc==1) ios::sync_with_stdio(false);
	FOR(i,argc-1) s+=argv[i+1],s+='\n';
	FOR(i,s.size()) ungetc(s[s.size()-1-i],stdin);
	solve(); return 0;
}

Submission Info

Judge Result