oj.uz

Submission #66453

# Submission time Handle Problem Language Result Execution time Memory
66453 2018-08-10T15:28:53 Z aquablitz11 Parachute rings (IOI12_rings) C++14
37 / 100
 1495 ms 96352 KB 
#include <bits/stdc++.h>
using namespace std;
using pii = pair<int, int>;
const int N = 1e6+10;
 
// graph data
 
int n;
vector<pii> E, ES;
vector<int> G[N];
 
int dfs(int u, int p, int s, int t)
{
    if (u == t)
        return 1;
    for (auto v : G[u]) if (v != p && (u != s || v != t)) {
        int r = dfs(v, u, s, t);
        if (r) return r+1;
    }
    return 0;
}
 
// dsu with copying for experimentation
 
int par[N], mfcnt, firstcycle;
int root(int u) {
    if (par[u] == u) return u;
    return par[u] = root(par[u]);
}
bool merge(int u, int v) {
    //fprintf(stderr, "merge(%d, %d)\n", u, v);
    int u0 = u, v0 = v;
    u = root(u), v = root(v);
    if (u == v) {
        if (++mfcnt == 1)
            firstcycle = dfs(u0, -1, u0, v0);
        return false;
    }
    par[u] = v;
    return true;
}
int _np[N], _nv[N], nmfcnt, tick;
int &np(int u) {
    if (_nv[u] != tick) {
        _np[u] = par[u];
        _nv[u] = tick;
    }
    return _np[u];
}
int nroot(int u) {
    if (np(u) == u) return u;
    return np(u) = nroot(np(u));
}
bool nmerge(int u, int v) {
    //fprintf(stderr, "nmerge(%d, %d)\n", u, v);
    u = nroot(u), v = nroot(v);
    if (u == v) return ++nmfcnt, false;
    np(u) = v;
    return true;
}
 
// state control (degree freq. histogram)
 
int cntok, cnt3, cnt4;
pii mxdeg(0, -1);
 
void testmod(int a, int b) {
    if (a <= 2) --cntok;
    if (a == 3) --cnt3;
    if (a >= 4) --cnt4;
    if (b <= 2) ++cntok;
    if (b == 3) ++cnt3;
    if (b >= 4) ++cnt4;
}
 
// rebuild dsu with exceptions
 
bool must_skip(int u) {
    if (mxdeg.first < 3)
        return false;
    if (u == mxdeg.second)
        return true;
    if (mxdeg.first == 3) {
        for (auto v : G[mxdeg.second]) if (v == u)
            return true;
    }
    return false;
}
 
void build_dsu() {
    //fprintf(stderr, "rebuild dsu!\n");
    ES.clear();
    for (int i = 0; i < n; ++i)
        par[i] = i;
    for (auto e : E) {
        int u = e.first, v = e.second;
        if (must_skip(u) || must_skip(v)) {
            ES.emplace_back(u, v);
            //fprintf(stderr, "skip edge %d %d\n", u, v);
            continue;
        }
        merge(e.first, e.second);
    }
}
 
bool modify(int u) {
    testmod(G[u].size()-1, G[u].size());
    if (G[u].size() > mxdeg.first) {
        mxdeg = pii(G[u].size(), u);
        if (mxdeg.first == 3 || mxdeg.first == 4)
            return true;
    }
    return false;
}
 
// testing functions
 
bool test(int u) {
    //fprintf(stderr, "test(%d)\n", u);
    testmod(G[u].size(), 0);
    for (auto v : G[u])
        testmod(G[v].size(), G[v].size()-1);
 
    bool ok = cnt3 == 0 && cnt4 == 0;
    ++tick;
    nmfcnt = mfcnt;
    if (ok) for (auto e : ES) {
        if (e.first == u || e.second == u) continue;
        if (!nmerge(e.first, e.second)) ok = false;
        if (!ok) break;
    }
    if (nmfcnt > 0) ok = false;
 
    testmod(0, G[u].size());
    for (auto v : G[u])
        testmod(G[v].size()-1, G[v].size());
 
    return ok;
}
 
// problem functions:
 
void Init(int n) {
    //fprintf(stderr, "Init(%d)\n", n);
    ::n = n;
    build_dsu();
}
 
void Link(int u, int v) {
    //fprintf(stderr, "Link(%d, %d)\n", u, v);
    G[u].push_back(v);
    G[v].push_back(u);
    bool m = modify(u) | modify(v);
    E.emplace_back(u, v);
    if (m)
        build_dsu();
    else if (!must_skip(u) && !must_skip(v))
        merge(u, v);
    else
        ES.emplace_back(u, v);
}
 
int CountCritical() {
    //fprintf(stderr, "CountCritical()\n");
    if (cnt3 > 4 || cnt4 > 1) return 0;
    if (mxdeg.first <= 2) {
        if (mfcnt > 1) return 0;
        else if (mfcnt == 1) return firstcycle;
        else if (mfcnt == 0) return n;
    }
    if (mxdeg.first == 3) {
        int cnt = 0;
        if (test(mxdeg.second)) ++cnt;
        for (auto v : G[mxdeg.second])
            if (test(v)) ++cnt;
        return cnt;
    }
    if (cnt4 > 1) return 0;
    return test(mxdeg.second) ? 1 : 0;
}

Compilation message

rings.cpp: In function 'bool modify(int)':
rings.cpp:108:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     if (G[u].size() > mxdeg.first) {
         ~~~~~~~~~~~~^~~~~~~~~~~~~

Subtask #1
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 23 ms 23800 KB Output is correct
2 Correct 25 ms 24188 KB Output is correct
3 Correct 25 ms 24264 KB Output is correct
4 Correct 22 ms 24264 KB Output is correct
5 Correct 24 ms 24308 KB Output is correct
6 Correct 25 ms 24452 KB Output is correct
7 Correct 21 ms 24452 KB Output is correct
8 Correct 24 ms 24452 KB Output is correct
9 Correct 23 ms 24452 KB Output is correct
10 Correct 29 ms 24452 KB Output is correct

Subtask #2
17.0 / 17.0

# Verdict Execution time Memory Grader output
1 Correct 470 ms 46516 KB Output is correct
2 Correct 1048 ms 58564 KB Output is correct
3 Correct 1262 ms 62828 KB Output is correct
4 Correct 1174 ms 67252 KB Output is correct
5 Correct 1270 ms 68656 KB Output is correct
6 Correct 1495 ms 96352 KB Output is correct
7 Correct 1289 ms 96352 KB Output is correct
8 Correct 1140 ms 96352 KB Output is correct
9 Correct 1280 ms 96352 KB Output is correct
10 Correct 843 ms 96352 KB Output is correct

Subtask #3
0 / 18.0

# Verdict Execution time Memory Grader output
1 Correct 23 ms 23800 KB Output is correct
2 Correct 25 ms 24188 KB Output is correct
3 Correct 25 ms 24264 KB Output is correct
4 Correct 22 ms 24264 KB Output is correct
5 Correct 24 ms 24308 KB Output is correct
6 Correct 25 ms 24452 KB Output is correct
7 Correct 21 ms 24452 KB Output is correct
8 Correct 24 ms 24452 KB Output is correct
9 Correct 23 ms 24452 KB Output is correct
10 Correct 29 ms 24452 KB Output is correct
11 Correct 25 ms 96352 KB Output is correct
12 Incorrect 28 ms 96352 KB Output isn't correct
13 Halted 0 ms 0 KB -

Subtask #4
0 / 14.0

# Verdict Execution time Memory Grader output
1 Correct 23 ms 23800 KB Output is correct
2 Correct 25 ms 24188 KB Output is correct
3 Correct 25 ms 24264 KB Output is correct
4 Correct 22 ms 24264 KB Output is correct
5 Correct 24 ms 24308 KB Output is correct
6 Correct 25 ms 24452 KB Output is correct
7 Correct 21 ms 24452 KB Output is correct
8 Correct 24 ms 24452 KB Output is correct
9 Correct 23 ms 24452 KB Output is correct
10 Correct 29 ms 24452 KB Output is correct
11 Correct 25 ms 96352 KB Output is correct
12 Incorrect 28 ms 96352 KB Output isn't correct
13 Halted 0 ms 0 KB -

Subtask #5
0 / 31.0

# Verdict Execution time Memory Grader output
1 Correct 23 ms 23800 KB Output is correct
2 Correct 25 ms 24188 KB Output is correct
3 Correct 25 ms 24264 KB Output is correct
4 Correct 22 ms 24264 KB Output is correct
5 Correct 24 ms 24308 KB Output is correct
6 Correct 25 ms 24452 KB Output is correct
7 Correct 21 ms 24452 KB Output is correct
8 Correct 24 ms 24452 KB Output is correct
9 Correct 23 ms 24452 KB Output is correct
10 Correct 29 ms 24452 KB Output is correct
11 Correct 470 ms 46516 KB Output is correct
12 Correct 1048 ms 58564 KB Output is correct
13 Correct 1262 ms 62828 KB Output is correct
14 Correct 1174 ms 67252 KB Output is correct
15 Correct 1270 ms 68656 KB Output is correct
16 Correct 1495 ms 96352 KB Output is correct
17 Correct 1289 ms 96352 KB Output is correct
18 Correct 1140 ms 96352 KB Output is correct
19 Correct 1280 ms 96352 KB Output is correct
20 Correct 843 ms 96352 KB Output is correct
21 Correct 25 ms 96352 KB Output is correct
22 Incorrect 28 ms 96352 KB Output isn't correct
23 Halted 0 ms 0 KB -