oj.uz

Submission #66446

# Submission time Handle Problem Language Result Execution time Memory
66446 2018-08-10T15:14:42 Z aquablitz11 Parachute rings (IOI12_rings) C++14
20 / 100
 4000 ms 46564 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 (mxdeg.first <= 2) {
        int cnt = 0;
        for (int i = 0; i < n; ++i)
            if (test(i)) ++cnt;
        return cnt;
        /*if (mfcnt > 1) return 0;
        else if (mfcnt == 1) return firstcycle;
        else 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 23 ms 23800 KB Output is correct
2 Correct 24 ms 24188 KB Output is correct
3 Correct 25 ms 24256 KB Output is correct
4 Correct 31 ms 24256 KB Output is correct
5 Correct 118 ms 24256 KB Output is correct
6 Correct 343 ms 24332 KB Output is correct
7 Correct 22 ms 24332 KB Output is correct
8 Correct 194 ms 24348 KB Output is correct
9 Correct 25 ms 24348 KB Output is correct
10 Correct 24 ms 24348 KB Output is correct

Subtask #2
0 / 17.0

# Verdict Execution time Memory Grader output
1 Execution timed out 4014 ms 46564 KB Time limit exceeded
2 Halted 0 ms 0 KB -

Subtask #3
0 / 18.0

# Verdict Execution time Memory Grader output
1 Correct 23 ms 23800 KB Output is correct
2 Correct 24 ms 24188 KB Output is correct
3 Correct 25 ms 24256 KB Output is correct
4 Correct 31 ms 24256 KB Output is correct
5 Correct 118 ms 24256 KB Output is correct
6 Correct 343 ms 24332 KB Output is correct
7 Correct 22 ms 24332 KB Output is correct
8 Correct 194 ms 24348 KB Output is correct
9 Correct 25 ms 24348 KB Output is correct
10 Correct 24 ms 24348 KB Output is correct
11 Correct 1211 ms 46564 KB Output is correct
12 Execution timed out 4033 ms 46564 KB Time limit exceeded
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 24 ms 24188 KB Output is correct
3 Correct 25 ms 24256 KB Output is correct
4 Correct 31 ms 24256 KB Output is correct
5 Correct 118 ms 24256 KB Output is correct
6 Correct 343 ms 24332 KB Output is correct
7 Correct 22 ms 24332 KB Output is correct
8 Correct 194 ms 24348 KB Output is correct
9 Correct 25 ms 24348 KB Output is correct
10 Correct 24 ms 24348 KB Output is correct
11 Correct 1211 ms 46564 KB Output is correct
12 Execution timed out 4033 ms 46564 KB Time limit exceeded
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 24 ms 24188 KB Output is correct
3 Correct 25 ms 24256 KB Output is correct
4 Correct 31 ms 24256 KB Output is correct
5 Correct 118 ms 24256 KB Output is correct
6 Correct 343 ms 24332 KB Output is correct
7 Correct 22 ms 24332 KB Output is correct
8 Correct 194 ms 24348 KB Output is correct
9 Correct 25 ms 24348 KB Output is correct
10 Correct 24 ms 24348 KB Output is correct
11 Execution timed out 4014 ms 46564 KB Time limit exceeded
12 Halted 0 ms 0 KB -