Data_Structure/資料結構光碟檔/CH12/shortestPath.c

/* file name: shortestPath.c */
/* <20>Q<EFBFBD><51> Dijkstra <20>t<EFBFBD><74><EFBFBD>k<EFBFBD>D<EFBFBD>̵u<CCB5><75><EFBFBD>| */

#include <stdio.h>
#include <stdlib.h>

#define MAX_V 100   /*<2A>̤j<CCA4>`<60>I<EFBFBD><49>*/
#define VISITED 1
#define NOTVISITED 0
#define Infinite 1073741823

/* A[1..N][1..N] <20><><EFBFBD>ϧΪ<CFA7><CEAA>۾F<DBBE>x<EFBFBD>} */
/* D[i] i=1..N <20>Ψ<EFBFBD><CEA8>x<EFBFBD>s<EFBFBD>Y<EFBFBD>_<EFBFBD>l<EFBFBD><6C><EFBFBD>I<EFBFBD><49>i<EFBFBD>`<60>I<EFBFBD><49><EFBFBD>̵u<CCB5>Z<EFBFBD><5A> */
/* S[1..N] <20>ΨӰO<D3B0><4F><EFBFBD><EFBFBD><EFBFBD>I<EFBFBD>O<EFBFBD>_<EFBFBD>w<EFBFBD>g<EFBFBD><67><EFBFBD>X<EFBFBD>L */
/* P[1..N] <20>ΨӰO<D3B0><4F><EFBFBD>̪<EFBFBD><CCAA>g<EFBFBD>L<EFBFBD><4C><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>`<60>I */

long int A[MAX_V+1][MAX_V+1];
long int D[MAX_V+1];
long int S[MAX_V+1], P[MAX_V+1];
int source , sink , N;
int step = 1;

int top = -1;         /*<2A><><EFBFBD>|<7C><><EFBFBD><EFBFBD>*/
int Stack[MAX_V+1];   /*<2A><><EFBFBD>|<7C>Ŷ<EFBFBD>*/

void init(void);
int minD(void);
void output_step(void);
void output_path(void);
void push(int);
int pop(void);

int main(){
    int t,I;

    init();
    output_step();
	printf("\n");
    for (step =2;step <=N; step++) {
        /* minD <20>Ǧ^<5E>@<40><>t<EFBFBD>ϱoD[t] <20><><EFBFBD>̤p */
        t = minD();
        S[t] = VISITED;
        /* <20><><EFBFBD>X<EFBFBD>g<EFBFBD>Lt<4C>I<EFBFBD>|<7C>ϸ<EFBFBD><CFB8>|<7C>Y<EFBFBD>u<EFBFBD><75><EFBFBD>`<60>I*/
        for (I=1; I <= N; I++)
        if ((S[I] == NOTVISITED) && (D[t]+A[t][I] <= D[I])) {
            D[I] = D[t] + A[t][I];
            P[I] = t;
        }
        output_step();
        printf("\n");
    }
    output_path();

    return 0;
}

void init(){
    FILE *fptr;
    int i,j;
    int weight;

    fptr = fopen("shortestPath1.dat","r");
    if (fptr == NULL) {
        perror("shortestPath.dat");
        exit(1);
    }

    fscanf(fptr, "%d", &N);      /*Ū<><C5AA><EFBFBD>ϧθ`<60>I<EFBFBD><49>*/
    for (i=1; i<=N; i++ )
        for (j=1; j<=N; j++)
            A[i][j] = Infinite;  /*<2A>_<EFBFBD>lA[1..N][1..N]<5D>۾F<DBBE>x<EFBFBD>}*/
 
    while (fscanf(fptr,"%d %d %d", &i, &j, &weight) != EOF)
    A[i][j] = weight;             /*Ū<><C5AA>i<EFBFBD>`<60>I<EFBFBD><49>j<EFBFBD>`<60>I<EFBFBD><49><EFBFBD>vweight */
    fclose(fptr);

    printf("Enter source node : ");
    scanf("%d", &source);
    printf("Enter sink node : ");
    scanf("%d", &sink);

    /* <20>_<EFBFBD>l<EFBFBD>U<EFBFBD>}<7D>C<EFBFBD><43><EFBFBD><EFBFBD>*/
    for (i = 1; i <= N; i++) {
        S[i] = NOTVISITED;   /*<2A>U<EFBFBD><55><EFBFBD>I<EFBFBD>]<5D><><EFBFBD>|<7C><><EFBFBD><EFBFBD><EFBFBD>X*/
        D[i] = A[source][i]; /*<2A>O<EFBFBD><4F><EFBFBD>_<EFBFBD>l<EFBFBD><6C><EFBFBD>I<EFBFBD>ܦU<DCA6><55><EFBFBD>I<EFBFBD>̵u<CCB5>Z<EFBFBD><5A>*/
        P[i] = source;
    }
    S[source] = VISITED;     /*<2A>l<EFBFBD>_<EFBFBD>`<60>I<EFBFBD>]<5D><><EFBFBD>w<EFBFBD>g<EFBFBD><67><EFBFBD>X*/
    D[source] = 0;
}

int minD(){
    int i,t;
    long int minimum = Infinite;

    for (i=1; i<=N; i++)
        if ((S[i] == NOTVISITED) && D[i] < minimum) {
            minimum = D[i];
            t = i;
        }

    return t;
}

/* <20><><EFBFBD>ܥثe<D8AB><65>D<EFBFBD>}<7D>C<EFBFBD>PP<50>}<7D>C<EFBFBD><43><EFBFBD>p */
void output_step(){
    int i;

    printf("\n Step #%d",step);
    printf("\n================================================\n");
    for (i=1; i<=N; i++)
        printf("  D[%d]", i);
    printf("\n");
    for (i=1; i<=N; i++)
        if (D[i] == Infinite)
            printf("  ----");
        else
            printf("%6ld",D[i]);
    printf("\n================================================\n");
    for (i=1; i<=N; i++)
        printf("  P[%d]", i);
    printf("\n");
    for (i=1; i<=N;i++)
        printf("%6ld", P[i]);
}

/*<2A><><EFBFBD>̵ܳu<CCB5><75><EFBFBD>|*/
void output_path(){
    int node = sink;

    /*<2A>P<EFBFBD>_<EFBFBD>O<EFBFBD>_<EFBFBD>_<EFBFBD>l<EFBFBD><6C><EFBFBD>I<EFBFBD><49><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>I<EFBFBD>εL<CEB5><4C><EFBFBD>|<7C>ܲ<EFBFBD><DCB2>I*/
    if ((sink == source) || (D[sink] == Infinite)) {
        printf("\nNode %d has no Path to Node %d", source, sink);
        return;
    }

    printf("\n");
    printf(" The shortest  Path from V%d to V%d :", source, sink);
    printf("\n------------------------------------------\n");

    /*<2A>Ѳ<EFBFBD><D1B2>I<EFBFBD>}<7D>l<EFBFBD>N<EFBFBD>W<EFBFBD>@<40><><EFBFBD>g<EFBFBD>L<EFBFBD><4C><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>`<60>I<EFBFBD><49><EFBFBD>J<EFBFBD><4A><EFBFBD>|<7C>ܨ<EFBFBD><DCA8>_<EFBFBD>l<EFBFBD>`<60>I*/
    printf("  V%d", source);
    while (node != source) {
        push(node);
        node = P[node];
    }
    while(node != sink) {
        node = pop();
        printf(" --%ld-->",A[P[node]][node]);
        printf("V%d", node);
    }

    printf("\n Total length : %ld\n", D[sink]);
}

void push(int value){
    if (top >= MAX_V) {
        printf("Stack overflow!\n");
        exit(1);
    }
    else
        Stack[++top] = value;
}

int pop(){
    if (top < 0) {
        printf("Stack empty!\n");
        exit(1);
    }

    return Stack[top--];
}