oj.uz

Submission #66451

# Submission time Handle Problem Language Result Execution time Memory
66451 2018-08-10T15:23:34 Z aquablitz11 Parachute rings (IOI12_rings) C++14
20 / 100
 4000 ms 46540 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);
    u = root(u), v = root(v);
    if (u == v) {
        if (++mfcnt == 1)
            firstcycle = dfs(u, -1, u, v);
        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;*/

    for (int u = 0; u < n; ++u)
        par[u] = u;
    for (auto e : E) {
        if (e.first == u || e.second == u) continue;
        if (!merge(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) {
        int cnt = 0;
        for (int u = 0; u < n; ++u)
            if (test(u)) ++cnt;
        return cnt;
        /*for (int u = 0; u < n; ++u)
            par[u] = u;
        for (auto e : E)
            merge(e.first, e.second);*/
        /*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:107:21: 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 22 ms 23804 KB Output is correct
2 Correct 26 ms 24116 KB Output is correct
3 Correct 25 ms 24128 KB Output is correct
4 Correct 33 ms 24128 KB Output is correct
5 Correct 158 ms 24148 KB Output is correct
6 Correct 365 ms 24276 KB Output is correct
7 Correct 25 ms 24276 KB Output is correct
8 Correct 193 ms 24276 KB Output is correct
9 Correct 25 ms 24348 KB Output is correct
10 Correct 25 ms 24348 KB Output is correct

Subtask #2
0 / 17.0

# Verdict Execution time Memory Grader output
1 Execution timed out 4082 ms 46540 KB Time limit exceeded
2 Halted 0 ms 0 KB -

Subtask #3
0 / 18.0

# Verdict Execution time Memory Grader output
1 Correct 22 ms 23804 KB Output is correct
2 Correct 26 ms 24116 KB Output is correct
3 Correct 25 ms 24128 KB Output is correct
4 Correct 33 ms 24128 KB Output is correct
5 Correct 158 ms 24148 KB Output is correct
6 Correct 365 ms 24276 KB Output is correct
7 Correct 25 ms 24276 KB Output is correct
8 Correct 193 ms 24276 KB Output is correct
9 Correct 25 ms 24348 KB Output is correct
10 Correct 25 ms 24348 KB Output is correct
11 Correct 1220 ms 46540 KB Output is correct
12 Execution timed out 4025 ms 46540 KB Time limit exceeded
13 Halted 0 ms 0 KB -

Subtask #4
0 / 14.0

# Verdict Execution time Memory Grader output
1 Correct 22 ms 23804 KB Output is correct
2 Correct 26 ms 24116 KB Output is correct
3 Correct 25 ms 24128 KB Output is correct
4 Correct 33 ms 24128 KB Output is correct
5 Correct 158 ms 24148 KB Output is correct
6 Correct 365 ms 24276 KB Output is correct
7 Correct 25 ms 24276 KB Output is correct
8 Correct 193 ms 24276 KB Output is correct
9 Correct 25 ms 24348 KB Output is correct
10 Correct 25 ms 24348 KB Output is correct
11 Correct 1220 ms 46540 KB Output is correct
12 Execution timed out 4025 ms 46540 KB Time limit exceeded
13 Halted 0 ms 0 KB -

Subtask #5
0 / 31.0

# Verdict Execution time Memory Grader output
1 Correct 22 ms 23804 KB Output is correct
2 Correct 26 ms 24116 KB Output is correct
3 Correct 25 ms 24128 KB Output is correct
4 Correct 33 ms 24128 KB Output is correct
5 Correct 158 ms 24148 KB Output is correct
6 Correct 365 ms 24276 KB Output is correct
7 Correct 25 ms 24276 KB Output is correct
8 Correct 193 ms 24276 KB Output is correct
9 Correct 25 ms 24348 KB Output is correct
10 Correct 25 ms 24348 KB Output is correct
11 Execution timed out 4082 ms 46540 KB Time limit exceeded
12 Halted 0 ms 0 KB -