廣度優先搜索遍歷連通圖

//廣度優先搜索遍歷連通圖
#include <iostream>
using namespace std;

#define MVNum 100
#define MAXQSIZE 100

typedef char VerTexType;
typedef int ArcType;
bool visited[MVNum];

typedef struct {
    VerTexType vexs[MVNum];
        ArcType arcs[MVNum][MVNum];
    int vexnum, arcnum;
}Graph;

typedef struct {
    ArcType* base;
    int front;
    int rear;
}sqQueue;

void InitQueue(sqQueue& Q) {
    Q.base = new ArcType[MAXQSIZE];
    if (!Q.base)
        exit(1);
    Q.front = Q.rear = 0;
}

void EnQueue(sqQueue& Q, ArcType e) {
    if ((Q.rear + 1) % MAXQSIZE == Q.front)
        return;
    Q.base[Q.rear] = e;
    Q.rear = (Q.rear + 1) % MAXQSIZE;
}

bool QueueEmpty(sqQueue Q) {
    if (Q.rear == Q.front)
        return true;
    return false;
}

void Dequeue(sqQueue& Q, ArcType& u) {
    u = Q.base[Q.front];
    Q.front = (Q.front + 1) % MAXQSIZE;
}

int LocateVex(Graph G, VerTexType v) {
    for (int i = 0;i < G.vexnum;++i)
        if (G.vexs[i] == v)
            return i;
    return -1;
}

void CreateUDN(Graph& G) {
    int i, j, k;
    cout << "請輸入總頂點數，總邊數，以空格隔開:";
    cin >> G.vexnum >> G.arcnum;
    cout << endl;
    cout << "輸入點的名稱，如a" << endl;
    for (i = 0;i < G.vexnum;++i) {
        cout << "請輸入第" << (i + 1) << "個點的名稱:";
        cin >> G.vexs[i];
    }
    cout << endl;
    for (i = 0;i < G.vexnum;++i) {
        for (j = 0;j < G.vexnum;++i)
            G.arcs[i][j] = 0;
    }
    cout << "輸入邊依附的頂點，如a b" << endl;
    for (k = 0;k < G.vexnum;k++) {
        VerTexType v1, v2;
        cout << "請輸入第" << (k + 1) << "條邊依附的頂點:";
        cin >> v1 >> v2;
        i = LocateVex(G, v1);
        j = LocateVex(G, v2);
        G.arcs[i][j] = 1;
        G.arcs[j][i] = G.arcs[i][j];
    }
}

int FirstAdjVex(Graph G, int v) {
    int i;
    for (i = 0;i < G.vexnum;++i) {
        if (G.arcs[v][i] == 1 && visited[i] == false)
            return i;
    }
    return -1;
}

int NextAdjVex(Graph G, int u, int w) {
    int i;
    for (i = w;i < G.vexnum;++i) {
        if (G.arcs[u][i] == 1 && visited[i] == false)
            return i;
    }
    return -1;
}

void BFS(Graph G, int v) {
    sqQueue Q;
    ArcType u;
    ArcType w;

    cout << G.vexs[v] << "  ";
    visited[v] = true;
    InitQueue(Q);
    EnQueue(Q, v);
    while (!QueueEmpty(Q)) {
        Dequeue(Q, u);
        for (w = FirstAdjVex(G, u);w >= 0;w = NextAdjVex(G, u, w)) {
            if (!visited[w]) {
                cout << G.vexs[w] << "   ";
                visited[w] = true;
                EnQueue(Q, w);
            }
        }
    }
}

int main() {
    cout << "廣度優先搜索遍歷連通圖";
    Graph G;
    CreateUDN(G);
    cout << endl;
    cout << "無向連通圖G建立完成！" << endl;

    cout << "請輸入遍歷連通圖的起始點：";
    VerTexType c;
    cin >> c;

    int i;
    for (i = 0;i < G.vexnum;++i) {
        if (c == G.vexs[i])
            break;
    }
    cout << endl;
    while (i >= G.vexnum) {
        cout << "該點不存在，請從新輸入！" << endl;
        cout << "請輸入遍歷連通圖的起始點：";
        cin >> c;
        for (i = 0;i < G.vexnum;++i) {
            if (c == G.vexs[i])
                break;
        }
    }
    cout << "廣度優先搜索遍歷連通圖結果：" << endl;
    BFS(G, i);

    cout << endl;
    return 0;
}