Cod sursa(job #1214819)

Utilizator CosminRusuCosmin Rusu CosminRusu Data 31 iulie 2014 15:19:47
Problema Flux maxim Scor 40
Compilator cpp Status done
Runda Arhiva educationala Marime 3.49 kb
#include <fstream>
#include <iostream>
#include <vector>
#include <bitset>
#include <string.h>
#include <algorithm>
#include <iomanip>
#include <math.h>
#include <time.h>
#include <stdlib.h>
#include <set>
#include <map>
#include <string>
#include <queue>
#include <unordered_map>

using namespace std;

const char infile[] = "maxflow.in";
const char outfile[] = "maxflow.out";

const int MAXN = 100005;
const int oo = 0x3f3f3f3f;

ifstream fin(infile);
ofstream fout(outfile);

typedef vector<int> ggg[MAXN];
typedef vector<int> :: iterator It;

const inline int min(const int &a, const int &b) { if( a > b ) return b;   return a; }
const inline int max(const int &a, const int &b) { if( a < b ) return b;   return a; }
const inline void Get_min(int &a, const int b)    { if( a > b ) a = b; }
const inline void Get_max(int &a, const int b)    { if( a < b ) a = b; }

class Graph {
public:
    Graph() {

    }
    Graph(int N) {
        g.resize(N);
        father.resize(N);
        #ifdef debug
        used.resize(N);
        #endif
        n = N;
    }
    void build(int N) {
        g.resize(N);
        father.resize(N);
        #ifdef debug
        used.resize(N);
        #endif
        n = N;
    }
    void addEdge(int x, int y, int capacity) {
        g[x].push_back(y);
        //g[y].push_back(x);
        _capacity[x][y] = capacity;
    }
    bool bfs(int source, int sink) {
        #ifdef debug
        fill(used.begin(), used.end(), 0);// debug
        #else
        used.reset();
        #endif
        q.push(source);
        used[source] = 1;
        while(!q.empty()) {
            int node = q.front();
            q.pop();
            if(node == sink)
                continue;
            for(It it = g[node].begin(), fin = g[node].end(); it != fin ; ++ it)
                if(!used[*it] && _capacity[node][*it] > _flow[node][*it]) {
                    used[*it] = 1;
                    father[*it] = node;
                    q.push(*it);
                }
        }
        return used[sink];
    }
    int getMaxFlow(int source, int sink) {
        int maxFlow = 0;
        while(bfs(source, sink)) {
            for(It it = g[sink].begin(), fin = g[sink].end() ; it != fin ; ++ it) {
                if(!used[*it] || _capacity[*it][sink] <= _flow[*it][sink])
                    continue;
                int bottleneck = oo;
                father[sink] = *it;
                for(int i = sink ; i != source ; i = father[i])
                    bottleneck = min(bottleneck, _capacity[father[i]][i] - _flow[father[i]][i]);
                if(!bottleneck)
                    continue;
                for(int i = sink ; i != source ; i = father[i]) {
                    _flow[father[i]][i] += bottleneck;
                    _flow[i][father[i]] -= bottleneck;
                }
                maxFlow += bottleneck;
            }
        }
        return maxFlow;
    }
private:
    queue <int> q;
    #ifdef debug
    vector <bool> used;
    #else
    bitset <MAXN> used;
    #endif
    int n;
    vector <vector <int> > g;
    vector <int> father;
    map <int, map<int, int> > _capacity, _flow;
} G;

int main() {
    int n, m;
    fin >> n >> m;
    G.build(n);
    while(m -- ) {
        int x, y, c;
        fin >> x >> y >> c;
        G.addEdge(x - 1, y - 1, c);
        G.addEdge(y - 1, x - 1, 0);
    }
    fout << G.getMaxFlow(0, n - 1) << '\n';
    fin.close();
    fout.close();
    return 0;
}