oj.uz

Submission #66456

# Submission time Handle Problem Language Result Execution time Memory
66456 2018-08-10T15:55:31 Z aquablitz11 Parachute rings (IOI12_rings) C++14
37 / 100
 1327 ms 96376 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;
    }*/
    ++tick;
    for (int i = 0; i < n; ++i)
        np(i) = i;
    for (auto e : E) {
        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 27 ms 23928 KB Output is correct
2 Correct 25 ms 24216 KB Output is correct
3 Correct 25 ms 24224 KB Output is correct
4 Correct 29 ms 24224 KB Output is correct
5 Correct 23 ms 24224 KB Output is correct
6 Correct 26 ms 24624 KB Output is correct
7 Correct 22 ms 24624 KB Output is correct
8 Correct 24 ms 24624 KB Output is correct
9 Correct 24 ms 24624 KB Output is correct
10 Correct 26 ms 24624 KB Output is correct

Subtask #2
17.0 / 17.0

# Verdict Execution time Memory Grader output
1 Correct 497 ms 46580 KB Output is correct
2 Correct 1004 ms 65000 KB Output is correct
3 Correct 1185 ms 65000 KB Output is correct
4 Correct 1212 ms 67140 KB Output is correct
5 Correct 1174 ms 68456 KB Output is correct
6 Correct 1310 ms 96376 KB Output is correct
7 Correct 1163 ms 96376 KB Output is correct
8 Correct 1231 ms 96376 KB Output is correct
9 Correct 1327 ms 96376 KB Output is correct
10 Correct 882 ms 96376 KB Output is correct

Subtask #3
0 / 18.0

# Verdict Execution time Memory Grader output
1 Correct 27 ms 23928 KB Output is correct
2 Correct 25 ms 24216 KB Output is correct
3 Correct 25 ms 24224 KB Output is correct
4 Correct 29 ms 24224 KB Output is correct
5 Correct 23 ms 24224 KB Output is correct
6 Correct 26 ms 24624 KB Output is correct
7 Correct 22 ms 24624 KB Output is correct
8 Correct 24 ms 24624 KB Output is correct
9 Correct 24 ms 24624 KB Output is correct
10 Correct 26 ms 24624 KB Output is correct
11 Correct 32 ms 96376 KB Output is correct
12 Correct 31 ms 96376 KB Output is correct
13 Correct 46 ms 96376 KB Output is correct
14 Incorrect 29 ms 96376 KB Output isn't correct
15 Halted 0 ms 0 KB -

Subtask #4
0 / 14.0

# Verdict Execution time Memory Grader output
1 Correct 27 ms 23928 KB Output is correct
2 Correct 25 ms 24216 KB Output is correct
3 Correct 25 ms 24224 KB Output is correct
4 Correct 29 ms 24224 KB Output is correct
5 Correct 23 ms 24224 KB Output is correct
6 Correct 26 ms 24624 KB Output is correct
7 Correct 22 ms 24624 KB Output is correct
8 Correct 24 ms 24624 KB Output is correct
9 Correct 24 ms 24624 KB Output is correct
10 Correct 26 ms 24624 KB Output is correct
11 Correct 32 ms 96376 KB Output is correct
12 Correct 31 ms 96376 KB Output is correct
13 Correct 46 ms 96376 KB Output is correct
14 Incorrect 29 ms 96376 KB Output isn't correct
15 Halted 0 ms 0 KB -

Subtask #5
0 / 31.0

# Verdict Execution time Memory Grader output
1 Correct 27 ms 23928 KB Output is correct
2 Correct 25 ms 24216 KB Output is correct
3 Correct 25 ms 24224 KB Output is correct
4 Correct 29 ms 24224 KB Output is correct
5 Correct 23 ms 24224 KB Output is correct
6 Correct 26 ms 24624 KB Output is correct
7 Correct 22 ms 24624 KB Output is correct
8 Correct 24 ms 24624 KB Output is correct
9 Correct 24 ms 24624 KB Output is correct
10 Correct 26 ms 24624 KB Output is correct
11 Correct 497 ms 46580 KB Output is correct
12 Correct 1004 ms 65000 KB Output is correct
13 Correct 1185 ms 65000 KB Output is correct
14 Correct 1212 ms 67140 KB Output is correct
15 Correct 1174 ms 68456 KB Output is correct
16 Correct 1310 ms 96376 KB Output is correct
17 Correct 1163 ms 96376 KB Output is correct
18 Correct 1231 ms 96376 KB Output is correct
19 Correct 1327 ms 96376 KB Output is correct
20 Correct 882 ms 96376 KB Output is correct
21 Correct 32 ms 96376 KB Output is correct
22 Correct 31 ms 96376 KB Output is correct
23 Correct 46 ms 96376 KB Output is correct
24 Incorrect 29 ms 96376 KB Output isn't correct
25 Halted 0 ms 0 KB -