oj.uz

Submission #66455

# Submission time Handle Problem Language Result Execution time Memory
66455 2018-08-10T15:39:51 Z aquablitz11 Parachute rings (IOI12_rings) C++14
37 / 100
 1341 ms 96316 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
 
bool ffc = true;
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 && ffc)
            firstcycle = dfs(u0, -1, u0, v0);
        return false;
    }
    par[u] = v;
    return true;
}
int _np[N], _nv[N], 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 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();
    mfcnt = 0;
    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) {
            ffc = false;
            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;
    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;
    }
 
    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 (mfcnt > 0) return 0;
    if (mxdeg.first == 3) {
        int cnt = 0;
        if (test(mxdeg.second)) ++cnt;
        for (auto v : G[mxdeg.second])
            if (test(v)) ++cnt;
        return cnt;
    }
    return test(mxdeg.second) ? 1 : 0;
}

Compilation message

rings.cpp: In function 'bool modify(int)':
rings.cpp:110:21: 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 24 ms 24208 KB Output is correct
3 Correct 24 ms 24252 KB Output is correct
4 Correct 23 ms 24252 KB Output is correct
5 Correct 23 ms 24252 KB Output is correct
6 Correct 23 ms 24428 KB Output is correct
7 Correct 21 ms 24428 KB Output is correct
8 Correct 24 ms 24428 KB Output is correct
9 Correct 24 ms 24428 KB Output is correct
10 Correct 24 ms 24428 KB Output is correct

Subtask #2
17.0 / 17.0

# Verdict Execution time Memory Grader output
1 Correct 431 ms 46516 KB Output is correct
2 Correct 958 ms 58532 KB Output is correct
3 Correct 1177 ms 62852 KB Output is correct
4 Correct 1177 ms 67092 KB Output is correct
5 Correct 1202 ms 68416 KB Output is correct
6 Correct 1341 ms 96316 KB Output is correct
7 Correct 1241 ms 96316 KB Output is correct
8 Correct 1177 ms 96316 KB Output is correct
9 Correct 1221 ms 96316 KB Output is correct
10 Correct 834 ms 96316 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 24 ms 24208 KB Output is correct
3 Correct 24 ms 24252 KB Output is correct
4 Correct 23 ms 24252 KB Output is correct
5 Correct 23 ms 24252 KB Output is correct
6 Correct 23 ms 24428 KB Output is correct
7 Correct 21 ms 24428 KB Output is correct
8 Correct 24 ms 24428 KB Output is correct
9 Correct 24 ms 24428 KB Output is correct
10 Correct 24 ms 24428 KB Output is correct
11 Correct 23 ms 96316 KB Output is correct
12 Correct 27 ms 96316 KB Output is correct
13 Correct 29 ms 96316 KB Output is correct
14 Incorrect 24 ms 96316 KB Output isn't correct
15 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 24 ms 24208 KB Output is correct
3 Correct 24 ms 24252 KB Output is correct
4 Correct 23 ms 24252 KB Output is correct
5 Correct 23 ms 24252 KB Output is correct
6 Correct 23 ms 24428 KB Output is correct
7 Correct 21 ms 24428 KB Output is correct
8 Correct 24 ms 24428 KB Output is correct
9 Correct 24 ms 24428 KB Output is correct
10 Correct 24 ms 24428 KB Output is correct
11 Correct 23 ms 96316 KB Output is correct
12 Correct 27 ms 96316 KB Output is correct
13 Correct 29 ms 96316 KB Output is correct
14 Incorrect 24 ms 96316 KB Output isn't correct
15 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 24 ms 24208 KB Output is correct
3 Correct 24 ms 24252 KB Output is correct
4 Correct 23 ms 24252 KB Output is correct
5 Correct 23 ms 24252 KB Output is correct
6 Correct 23 ms 24428 KB Output is correct
7 Correct 21 ms 24428 KB Output is correct
8 Correct 24 ms 24428 KB Output is correct
9 Correct 24 ms 24428 KB Output is correct
10 Correct 24 ms 24428 KB Output is correct
11 Correct 431 ms 46516 KB Output is correct
12 Correct 958 ms 58532 KB Output is correct
13 Correct 1177 ms 62852 KB Output is correct
14 Correct 1177 ms 67092 KB Output is correct
15 Correct 1202 ms 68416 KB Output is correct
16 Correct 1341 ms 96316 KB Output is correct
17 Correct 1241 ms 96316 KB Output is correct
18 Correct 1177 ms 96316 KB Output is correct
19 Correct 1221 ms 96316 KB Output is correct
20 Correct 834 ms 96316 KB Output is correct
21 Correct 23 ms 96316 KB Output is correct
22 Correct 27 ms 96316 KB Output is correct
23 Correct 29 ms 96316 KB Output is correct
24 Incorrect 24 ms 96316 KB Output isn't correct
25 Halted 0 ms 0 KB -