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답안 #198796

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
198796 2020-01-27T17:18:31 Z arnold518 Islands (IOI08_islands) C++14
100 / 100
 969 ms 131072 KB 
#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

const int MAXN = 1e6;

int N;
vector<pii> adj[MAXN+10];
pii to[MAXN+10];
ll ans, val;

bool vis[MAXN+10];

ll dfs(int now, ll dep)
{
	vis[now]=true;
	ll ret=dep;

	pll t(0, 0);

	for(auto nxt : adj[now])
	{
		if(vis[nxt.first]) continue;
		ll p=dfs(nxt.first, dep+nxt.second);
		ret=max(ret, p);
		if(p>t.first) t.second=t.first, t.first=p;
		else if(p>t.second) t.second=p;
	}
	val=max(val, t.first+t.second-dep-dep);
	return ret;
}

int main()
{
	int i, j;

	scanf("%d", &N);
	for(i=1; i<=N; i++)
	{
		int u=i, v, w;
		scanf("%d%d", &v, &w);
		to[u]={v, w};
		adj[v].push_back({u, w});
	}

	for(i=1; i<=N; i++)
	{
		if(vis[i]) continue;

		int now=i;
		vector<int> cyc;
		while(!vis[now])
		{
			cyc.push_back(now);
			vis[now]=1;
			now=to[now].first;
		}

		reverse(cyc.begin(), cyc.end());
		while(!cyc.empty() && cyc.back()!=now) vis[cyc.back()]=0, cyc.pop_back();
		reverse(cyc.begin(), cyc.end());

		vector<ll> A, D;
		ll s=0; val=0;

		D.push_back(0);
		for(auto it : cyc) A.push_back(dfs(it, 0));
		for(auto it : cyc) D.push_back(D.back()+to[it].second), s+=to[it].second;
		D.pop_back();

		ll t=-1e18;
		for(j=0; j<cyc.size(); j++)
		{
			if(j) val=max(val, D[j]+A[j]+t);
			t=max(t, A[j]-D[j]);
		}

		t=-1e18;
		for(j=0; j<cyc.size(); j++)
		{
			if(j) val=max(val, s-D[j]+A[j]+t);
			t=max(t, D[j]+A[j]);
		}

		ans+=val;
	}
	printf("%lld", ans);
}

Compilation message

islands.cpp: In function 'int main()':
islands.cpp:75:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(j=0; j<cyc.size(); j++)
            ~^~~~~~~~~~~
islands.cpp:82:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(j=0; j<cyc.size(); j++)
            ~^~~~~~~~~~~
islands.cpp:40:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &N);
  ~~~~~^~~~~~~~~~
islands.cpp:44:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d", &v, &w);
   ~~~~~^~~~~~~~~~~~~~~~

Subtask #1
33.0 / 33.0

# 결과 실행 시간 메모리 Grader output
1 Correct 21 ms 23800 KB Output is correct
2 Correct 20 ms 23800 KB Output is correct
3 Correct 21 ms 23800 KB Output is correct
4 Correct 26 ms 23928 KB Output is correct
5 Correct 20 ms 23800 KB Output is correct
6 Correct 21 ms 23800 KB Output is correct
7 Correct 19 ms 23800 KB Output is correct
8 Correct 21 ms 23800 KB Output is correct
9 Correct 22 ms 23928 KB Output is correct
10 Correct 19 ms 23800 KB Output is correct
11 Correct 21 ms 23804 KB Output is correct

Subtask #2
3.0 / 3.0

# 결과 실행 시간 메모리 Grader output
1 Correct 21 ms 23800 KB Output is correct
2 Correct 22 ms 23928 KB Output is correct

Subtask #3
4.0 / 4.0

# 결과 실행 시간 메모리 Grader output
1 Correct 20 ms 23928 KB Output is correct
2 Correct 21 ms 23928 KB Output is correct

Subtask #4
10.0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 27 ms 24312 KB Output is correct
2 Correct 35 ms 25208 KB Output is correct
3 Correct 31 ms 24440 KB Output is correct
4 Correct 26 ms 24056 KB Output is correct

Subtask #5
10.0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 48 ms 25720 KB Output is correct
2 Correct 79 ms 27436 KB Output is correct

Subtask #6
10.0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 103 ms 30044 KB Output is correct
2 Correct 111 ms 35296 KB Output is correct
3 Correct 128 ms 35560 KB Output is correct

Subtask #7
10.0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 184 ms 36580 KB Output is correct
2 Correct 206 ms 42216 KB Output is correct
3 Correct 230 ms 54600 KB Output is correct
4 Correct 283 ms 52444 KB Output is correct

Subtask #8
10.0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 338 ms 40500 KB Output is correct
2 Correct 707 ms 65632 KB Output is correct
3 Correct 330 ms 46848 KB Output is correct
4 Correct 395 ms 60896 KB Output is correct
5 Correct 400 ms 58976 KB Output is correct
6 Correct 879 ms 52856 KB Output is correct
7 Correct 434 ms 70372 KB Output is correct

Subtask #9
10.0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 500 ms 131072 KB Output is correct
2 Correct 464 ms 95476 KB Output is correct
3 Correct 464 ms 103504 KB Output is correct
4 Correct 578 ms 78968 KB Output is correct
5 Correct 408 ms 72520 KB Output is correct
6 Correct 404 ms 70256 KB Output is correct
7 Correct 969 ms 68448 KB Output is correct