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Submission #1056531

# Submission time Handle Problem Language Result Execution time Memory
1056531 2024-08-13T09:54:46 Z lovrot Islands (IOI08_islands) C++17
80 / 100
 286 ms 131072 KB 
#include <cstdio> 
#include <vector>
#include <algorithm> 
#include <set>

#define debug(...) //fprintf(stderr, __VA_ARGS__)
#define X first
#define Y second
#define PB push_back

using namespace std;

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

const int N = 1e6 + 10;

int n, deg[N], to[N], weg[N]; 
vector<pii> g[N];

int cyci;
pii cyc[N];

void push_back(pii a) { 
	cyc[cyci++] = a;
}

void clear() {
	cyci = 0;
}

char bio[N];

int dfs(int u, int p) { 
	bio[u] = 1;
	for(pii &e : g[u]) { 
		int v = e.X, w = e.Y;
		if(w != p) { 
			if(bio[v]) { 
				push_back({e.X, weg[e.Y]});
//				cyc.PB({e.X, weg[e.Y]});
				return v;
			} else {
				int res = dfs(v, w);
				if(res) { 
					push_back({e.X, weg[e.Y]});					
//					cyc.PB({e.X, weg[e.Y]});
					return res != u ? res : 0;
				}
			}
		}
	}
	bio[u] = 0;
	return 0;
}

void mark(int u) { 
	bio[u] = 2;
	for(pii e : g[u]) { 
		if(bio[e.X] != 2) { 
			mark(e.X);
		}
	}
}

ll dep[N], ans_;

ll depth(int u, int p) { 
	ll max_ = 0;
	for(pii e : g[u]) { 
		int v = e.X, w = e.Y;
		if(w != p && !bio[v]) { 
			ll res = (ll) weg[w] + depth(v, w);
			if(dep[u] < res) { 
				max_ = dep[u]; 
				dep[u] = res;
			} else if(max_ < res) { 
				max_ = res;
			}
		}
	}
	ans_ = max(ans_, dep[u] + max_);
	return dep[u];
}

multiset<ll> s;

int main() { 
	scanf("%d", &n);

	for(int i = 1; i <= n; ++i) { 
		scanf("%d%d", to + i, weg + i);
		++deg[i];
		++deg[to[i]];
	}

	for(int i = 1; i <= n; ++i) { 
		g[i].reserve(deg[i]);
	}

	for(int i = 1; i <= n; ++i) {
		g[i].PB({to[i], i});
		g[to[i]].PB({i, i});
	}

	ll prf, prf_, len, ans = 0;
	int v, w;

	for(int i = 1; i <= n; ++i) { 
		if(bio[i]) { continue; }

		clear();
		s.clear();
		ans_ = 0;
		dfs(i, 0);

		for(int j = 0; j < cyci; ++j) { 
			depth(cyc[j].X, 0);
			debug("%d(%d, %lld)\n", e.X, e.Y, dep[e.X]);
		}

		mark(i);
		
		prf = 0;
		for(int j = 0; j < cyci; ++j) { 
			v = cyc[j].X;
			w = cyc[j].Y;	
			s.insert(dep[v] + prf);
			prf += w;
		}

		prf_ = 0;
		len = prf;
		for(int j = 0; j < cyci; ++j) { 
			v = cyc[j].X;
			w = cyc[j].Y;	
			s.erase(s.find(dep[v] + prf - len));

			ans_ = max(ans_, *prev(s.end()) + dep[v] - prf + len);

			s.insert(dep[v] + prf);
			prf += w;
		}

		ans += ans_;
	}

	printf("%lld\n", ans);
	return 0;
}

Compilation message

islands.cpp: In function 'int main()':
islands.cpp:106:10: warning: variable 'prf_' set but not used [-Wunused-but-set-variable]
  106 |  ll prf, prf_, len, ans = 0;
      |          ^~~~
islands.cpp:89:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   89 |  scanf("%d", &n);
      |  ~~~~~^~~~~~~~~~
islands.cpp:92:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   92 |   scanf("%d%d", to + i, weg + i);
      |   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
33.0 / 33.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 31064 KB Output is correct
2 Correct 4 ms 31068 KB Output is correct
3 Correct 5 ms 31068 KB Output is correct
4 Correct 3 ms 31068 KB Output is correct
5 Correct 3 ms 31068 KB Output is correct
6 Correct 4 ms 31224 KB Output is correct
7 Correct 4 ms 31064 KB Output is correct
8 Correct 4 ms 31068 KB Output is correct
9 Correct 4 ms 31068 KB Output is correct
10 Correct 4 ms 31068 KB Output is correct
11 Correct 4 ms 31064 KB Output is correct

Subtask #2
3.0 / 3.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 31324 KB Output is correct
2 Correct 4 ms 31068 KB Output is correct

Subtask #3
4.0 / 4.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 31320 KB Output is correct
2 Correct 5 ms 31684 KB Output is correct

Subtask #4
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 7 ms 32088 KB Output is correct
2 Correct 15 ms 36812 KB Output is correct
3 Correct 9 ms 34452 KB Output is correct
4 Correct 6 ms 31664 KB Output is correct

Subtask #5
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 18 ms 38236 KB Output is correct
2 Correct 29 ms 42320 KB Output is correct

Subtask #6
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 55 ms 48584 KB Output is correct
2 Correct 74 ms 56284 KB Output is correct
3 Correct 96 ms 67800 KB Output is correct

Subtask #7
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 91 ms 57940 KB Output is correct
2 Correct 162 ms 85740 KB Output is correct
3 Correct 252 ms 91728 KB Output is correct
4 Correct 259 ms 116820 KB Output is correct

Subtask #8
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 158 ms 90960 KB Output is correct
2 Runtime error 286 ms 131072 KB Execution killed with signal 9
3 Halted 0 ms 0 KB -

Subtask #9
0 / 10.0

# Verdict Execution time Memory Grader output
1 Runtime error 193 ms 131072 KB Execution killed with signal 9
2 Halted 0 ms 0 KB -