Submission #1821552

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Source Code Expand

#include <iostream>
#include <sstream>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <ctime>
#include <cstring>
#include <string>
#include <vector>
#include <stack>
#include <queue>
#include <deque>
#include <map>
#include <set>
#include <bitset>
#include <numeric>
#include <utility>
#include <iomanip>
#include <algorithm>
#include <functional>
using namespace std;

#define COUT(x) cout << #x << " = " << (x) << " (L" << __LINE__ << ")" << endl
#define EACH(i, s) for (__typeof__((s).begin()) i = (s).begin(); i != (s).end(); ++i)

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
template<class T1, class T2> ostream& operator << (ostream &s, pair<T1,T2> P)
{ return s << '<' << P.first << ", " << P.second << '>'; }
template<class T> ostream& operator << (ostream &s, vector<T> P)
{ for (int i = 0; i < P.size(); ++i) { if (i > 0) { s << " "; } s << P[i]; } return s; }
template<class T> ostream& operator << (ostream &s, vector<vector<T> > P)
{ for (int i = 0; i < P.size(); ++i) { s << endl << P[i]; } return s << endl; }
template<class T1, class T2> ostream& operator << (ostream &s, map<T1,T2> P)
{ EACH(it, P) { s << "<" << it->first << "->" << it->second << "> "; } return s << endl; }




const int MAX_V = 50;
struct Graph {
    int V;
    vector<int> list[MAX_V];
    
    Graph(int n = 0) : V(n) {}
    void init(int n = 0) {V = n; for (int i = 0; i < MAX_V; ++i) list[i].clear();}
    inline vector<int>& operator [] (int i) {return list[i];}
    
    void connect(int f, int t) {
        list[f].push_back(t);
        list[t].push_back(f);
    }
    
    friend ostream& operator << (ostream& s, const Graph& G) {
        s << endl; for (int i = 0; i < G.V; ++i) {s << i << " : " << G.list[i] << endl;}return s;
    }
};

Graph G;


int ConnectedCase(Graph &G, vector<bool> can);
int GeneralCase(Graph &G, vector<bool> can);

void dfs(Graph &G, int v, vector<bool> &seen, vector<bool> &comp, vector<bool> can) {
    seen[v] = true;
    for (int i = 0; i < G[v].size(); ++i) {
        int to = G[v][i];
        if (!seen[to] && can[to]) dfs(G, to, seen, comp, can);
    }
    comp[v] = true;
}

int ConnectedCase(Graph &G, vector<bool> can) {
    int pMax = -1, pMin = -1, Max = -1, Min = MAX_V+1, num = 0;
    for (int i = 0; i < G.V; ++i) {
        if (!can[i]) continue;
        int tnum = 0; ++num;
        for (int j = 0; j < G[i].size(); ++j) if (can[G[i][j]]) ++tnum;
        if (Max < tnum) Max = tnum, pMax = i;
        if (Min > tnum) Min = tnum, pMin = i;
    }
    if (num == 1) return 1;
    if (Max <= 2) {
        if (Min == 1) return (num+1)/2;
        else return num/2;
    }
    int res = 0;
    if (Min < 2) {
        vector<bool> ncan(G.V, 0);
        for (int i = 0; i < G.V; ++i) ncan[i] = can[i];
        ncan[pMin] = false;
        for (int i = 0; i < G[pMin].size(); ++i) ncan[G[pMin][i]] = false;
        res = max(res, GeneralCase(G, ncan) + 1);
    }
    else {
        vector<bool> ncan(G.V, 0);
        for (int i = 0; i < G.V; ++i) ncan[i] = can[i];
        ncan[pMax] = false;
        for (int i = 0; i < G[pMax].size(); ++i) ncan[G[pMax][i]] = false;
        int temp1 = GeneralCase(G, ncan);
        res = max(res, temp1 + 1);
        
        for (int i = 0; i < G.V; ++i) ncan[i] = can[i];
        ncan[pMax] = false;
        res = max(res, GeneralCase(G, ncan));
    }
    return res;
}

int GeneralCase(Graph &G, vector<bool> can) {
    if (G.V == 1) return 1;
    vector<bool> seen(G.V, 0);
    int res = 0;
    for (int i = 0; i < G.V; ++i) {
        if (!seen[i] && can[i]) {
            vector<bool> gcan(G.V, false);
            dfs(G, i, seen, gcan, can);
            res += ConnectedCase(G, gcan);
        }
    }
    return res;
}

int StableSet(Graph &G) {
    vector<bool> can(G.V, 1);
    return GeneralCase(G, can);
}

int N, M;

int main () {
    while (cin >> N >> M) {
        G.init(N);
        for (int i = 0; i < M; ++i) {
            int a, b;
            cin >> a >> b;
            --a, --b;
            G.connect(a, b);
        }
        cout << StableSet(G) << endl;
    }
}

Submission Info

Judge Result