graph-basic

打算使用STL中的vector，通过邻接链表的方式存储图。这里贴基本定义，以及depth-first-search和breadth-first-search的实现代码。

其他图的算法实现，就贴在各自的算法解释之后吧。喵。

#include <iostream>  
#include <vector>  
#include <set>  
#include <algorithm>
using namespace std;  
  
// define vertex in graph  
typedef struct Vertex {  
    int id;  
    vector<int> neighbors;  
    Vertex() {
    	id = -1;
	}  
    Vertex(int nid){
    	id = nid;
	}  
} Vertex;  
// define graph
typedef struct Graph {
    // Vertex of Graph  
    vector<Vertex> vertexes;
    // number of vertexes
    int nVertexes;
    bool isDAG;
    
	// construct function
    Graph(int n, bool isDAG) : nVertexes(n), isDAG(isDAG) { vertexes.resize(n); }  
  
    // add edge.
    bool addEdge(int id1, int id2) {  
        if (max(id1, id2) >= vertexes.size()) 
		    return false;  
        if (isDAG) {  
            vertexes[id1].neighbors.push_back(id2);  
        }  
        else {  
            vertexes[id1].neighbors.push_back(id2);  
            vertexes[id2].neighbors.push_back(id1);  
        }  
        return true;  
    }  
    
    // depth first search  
    vector<int> DFS(int start) {  
        set<int> visited;  
        vector<int> g, result;  
        g.push_back(start);   
        visited.insert(start);  
        result.push_back(start);  
        bool found;  
        while(g.size() > 0) {  
            int id = g[g.size()-1];           
            found = false;  
            for(int i = 0; i < vertexes[id].neighbors.size(); i++) {  
                int id1 = vertexes[id].neighbors[i];  
                if (visited.count(id1) == 0) {  
                    g.push_back(id1);  
                    result.push_back(id1);  
                    visited.insert(id1);    
                    found = true;  
                    break;  
                }  
            }  
            // all neighbors have been visited
            if (!found) {  
                int id2 = g[g.size()-1];  
                //result.push_back(-1 * id2);  
                //cout << "pop " << id2 << " ";  
                g.pop_back();  
            }  
        }  
        return result;  
    }
    
    // breadth first search 
    vector<int> BFS(int start) {  
		set<int> visited;  
        vector<int> g, result;
		// temporary store  
        g.push_back(start);  
        visited.insert(start);  
        while(g.size() > 0) {  
            int id = g[0];            
            g.erase(g.begin());  
            result.push_back(id);  
            for(int i = 0; i < vertexes[id].neighbors.size(); i++) {  
                int id1 = vertexes[id].neighbors[i];  
                // if id1 is unvisited
                if (visited.count(id1) == 0) {  
                    g.push_back(id1);  
                    visited.insert(id1);  
                }  
            }  
        }  
        return result;  
    }      
} Graph;  
  
int main() {  
    Graph g(8, true);  
    g.addEdge(0, 1);  
    g.addEdge(0, 3);  
    g.addEdge(1, 2);  
    g.addEdge(3, 4);  
    g.addEdge(3, 5);  
    //g.addEdge(4, 5);  
    //g.addEdge(4, 6);      
    g.addEdge(5, 6);  
    g.addEdge(5, 7);      
    //g.addEdge(6, 7);  
    vector<int> bv = g.BFS(0);  
    cout << "宽度优先搜索节点顺序：";  
    for(int j = 0; j < bv.size(); j++)  
        cout << bv[j] << " ";  
    cout << endl;  
    
    bv = g.DFS(0);
    for(int j = 0; j < bv.size(); j++)  
        cout << bv[j] << " ";  
    cout << endl; 
    
    cout << "深度优先搜索节点顺序：";  
    Graph g1(6, false);  
    g1.addEdge(0, 1);  
    g1.addEdge(0, 4);  
    g1.addEdge(0, 5);  
    g1.addEdge(1, 5);  
    g1.addEdge(4, 5);  
    g1.addEdge(5, 2);  
    g1.addEdge(5, 3);  
    g1.addEdge(2, 3);  
    vector<int> route = g1.DFS(0);  
    for(int i = 0; i < route.size(); i++)  
        cout << route[i] << " ";  
    cout << endl;  
   
    return 0;  
}