hdu_1532_Drainage Ditches

cxy7tv發表於2016-05-14
#include<iostream>  
#include<sstream>  
#include<string>  
#include<vector>  
#include<list>  
#include<set>  
#include<map>
#include<stack>  
#include<queue>  
#include<algorithm>  
#include<numeric>  
#include<cmath>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#pragma warning(disable:4996)  
using std::cin;
using std::cout;
using std::endl;
using std::stringstream;
using std::string;
using std::vector;
using std::list;
using std::pair;
using std::set;
using std::multiset;
using std::map;
using std::multimap;
using std::stack;
using std::queue;
using std::priority_queue;
const int MaxVexNum = 1000;
const int INF = 1000000000;
class Edge
{
public:
	int to, capacity, flow;
	Edge(int t, int c, int f)
	{
		to = t,capacity = c,flow = f;
	}
};
class Network
{
private:
	int vexnum, edgenum, source, destination,maxflow;
	vector<vector<Edge>>adjList;
public:
	void addEdge(int from, int to, int cap)
	{
		adjList[from].push_back({ to, cap, (int)adjList[to].size() });
		adjList[to].push_back({ from, 0, (int)adjList[from].size() - 1 });
	}
	Network()
	{
		adjList.resize(MaxVexNum);
		cin >> edgenum >> vexnum;
		source = 1, destination = vexnum;
		for (int i = 0; i < edgenum; i++)
		{
			int from, to, capacity;
			cin >> from >> to >> capacity;
			addEdge(from, to, capacity);
		}
	}
	int dfs(int src, int sink, int flow,vector<bool>&used)
	{
		if (src == sink)
		{
			return flow;
		}
		used[src] = true;
		for (int i = 0; i<adjList[src].size(); i++)
		{
			Edge &edge = adjList[src][i];
			if (!used[edge.to] && edge.capacity>0)
			{
				int minflow = dfs(edge.to, sink, std::min(flow, edge.capacity),used);
				if (minflow>0)
				{
					edge.capacity -= minflow;
					adjList[edge.to][edge.flow].capacity += minflow;
					return minflow;
				}
			}
		}
		return 0;
	}
	void getMaxFlow()
	{
		maxflow = 0;
		while (1)
		{
			vector<bool>used(MaxVexNum);
			int f = dfs(source, destination, INF,used);
			if (!f)
			{
				return;
			}
			maxflow += f;
		}
	}
	void print()
	{
		cout << maxflow << endl;
	}
};
int main()
{
	//freopen("input.txt", "r", stdin);
	char ch;
	while ((ch = cin.get()) != EOF)
	{
		ungetc(ch,stdin);
		Network network;
		network.getMaxFlow();
		network.print();
		cin.get();
	}
	return 0;
}