C++ 關鍵路徑

代碼實現

#include <iostream>
#include <cstdio>
#include <stack>
#include <string>
#include <windows.h>
using namespace std;
int vertex_num;
int edge_num;
struct Edge
{
    int edge_from;  // 頂點1
    int edge_to;    // 頂點2
    int value;      // 代價
};

struct Graph
{
    int *maxValue;   // 最長路徑值
    int *root;      // 存父節點
    int **matrix;   // 鄰接矩陣

} graph;

int find_array(string s[],string str,int index)
{
    for(int i=0; i<index; i++)
        if(s[i] == str)
            return i;
    return -1;
}

void criticalpath(Edge G[])
{
    int index = 0;
    for(int i=0; i<edge_num; i++)
    {
        int from =  G[i].edge_from;
        int to = G[i].edge_to;
        index = graph.maxValue[from];
        if(index + G[i].value > graph.maxValue[to])
        {
            graph.root[to] = from;
            graph.maxValue[to] = index + G[i].value;
        }
    }
}
int main()
{
    printf("案例:\n10 14\nA B 5\nA C 6\nB D 3\nC D 6\nC E 3\nD E 3\nD F 4\nD G 4\nE F 1\nE H 4\nF I 5\nG J 4\nH I 2\nI J 2\n");
    printf("請輸入頂點的個數:\n");
    scanf("%d", &vertex_num);
    int k = 0, temp;
    string *str = new string[vertex_num];
    graph.maxValue = new int[vertex_num];
    graph.root = new int [vertex_num];
    graph.matrix = new int *[vertex_num];
    for(int i=0; i<vertex_num; i++)
    {
        graph.matrix[i] = new int [vertex_num];
        for(int j=0; j<vertex_num; j++)
            graph.matrix[i][j] = -1;
        graph.root[i] = -1;
        graph.maxValue[i] = 0;
    }

    Edge *edge;
    printf("請輸入邊的個數:\n");
    scanf("%d", &edge_num);
    edge = new Edge[edge_num];
    printf("請以\"結點A 結點B 權值\"的格式輸入\n其中結點,權值爲正整數\n");
    for(int i=0; i<edge_num; i++)
    {
        string a,b;
        cin >> a >> b;
        temp = find_array(str, a, k);
        if(temp != -1)
            edge[i].edge_from = temp;
        else
        {
            str[k] = a;
            edge[i].edge_from = k++;
        }

        temp = find_array(str, b, k);
        if(temp != -1)
            edge[i].edge_to = temp;
        else
        {
            str[k] = b;
            edge[i].edge_to = k++;
        }
        cin >> edge[i].value;
        graph.matrix[edge[i].edge_from][edge[i].edge_to] = edge[i].value;
    }
    printf("鄰接矩陣:\n");
    for(int i=0; i<vertex_num; i++)
    {
        for(int j=0; j<vertex_num; j++)
            printf("%5d", graph.matrix[i][j]);
        cout << endl;
    }
    criticalpath(edge);
    printf("\n關鍵路徑:\n");
    for(int i=0; i<vertex_num; i++)
    {
        stack<string> path;
        path.push(str[i]);
        int index = graph.root[i];
        cout << str[0] << "到" << str[i] << "的最早開始時間: " << graph.maxValue[i] << endl;
        while(index != -1)
        {
            path.push(str[index]);
            index = graph.root[index];
        }
        cout << "路徑:";
        while(!path.empty())
        {
            cout << path.top();
            path.pop();
        }
        cout << endl;
    }
    delete[] str;
    for(int i=0; i<vertex_num; i++)
        delete[] graph.matrix[i];
    delete[] graph.matrix;
    delete[] edge;
    system("pause");
    return 0;
}