Submission #995586

---

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 A[101010],B[101010];
int L;
int did[101010];
int ok[101010];

set<pair<int,int>> S;

void solve() {
	int i,j,k,l,r,x,y; string s;
	
	cin>>N;
	FOR(i,N) cin>>A[i]>>B[i];
	
	if(A[0]!=0) return _P("-1\n");
	if(B[1]!=0) return _P("-1\n");
	if(A[1]!=B[0]) return _P("-1\n");
	L=A[1];
	ok[0]=ok[L]=1;
	did[0]=did[1]=1;
	
	S.insert({0,L});
	S.insert({L,0});
	vector<pair<int,int>> V;
	int ret=1;
	for(i=2;i<N;i++) {
		if(A[i]==0 || B[i]==0) return _P("-1\n");
		if(A[i]+B[i]<L) return _P("-1\n");
		if(A[i]+B[i]==L) {
			did[i]=1;
			if(ok[A[i]]==1) ret++;
			ok[A[i]]=1;
			ret++;
			S.insert({A[i],B[i]});
		}
		else {
			V.push_back({A[i]+B[i],i});
		}
	}
	FOR(i,L+1) if(ok[i]==0) return _P("-1\n");
	sort(ALL(V));
	FORR(r,V) {
		x = r.second;
		if((A[x]+B[x]-L)%2==0) {
			if(S.count({A[x]-1,B[x]-1})==0) return _P("-1\n");
			ret++;
			
		}
		else {
			if(S.count({A[x]-1,B[x]})==0 || S.count({A[x],B[x]-1})==0) return _P("-1\n");
			ret+=2;
		}
		S.insert({A[x],B[x]});
	}
	_P("%d\n",ret);
	
	
}


int main(int argc,char** argv){
	string s;int i;
	if(argc==1) ios::sync_with_stdio(false), cin.tie(0);
	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