proj/mag/harp/libs/matlab/mfile-mex/assignment/pointer.c

/* Assign a pointer link to a vertex.  Edge e joins a vertex in blossom */
/* u to a linked vertex. */

POINTER (u,v,e)
int u,v,e;

{   int i, del;

#ifdef DEBUG
    printf("Pointer u,v,e=%d %d %d-%d\n",u,v,END[OPPEDGE(e)],END[e]);
#endif

    LINK[u] = -DUMMYEDGE;
    NEXTVTX[LASTVTX[u]] = DUMMYVERTEX;
    NEXTVTX[LASTVTX[v]] = DUMMYVERTEX;
    
    if (LASTVTX[u] != u) {
    i = MATE[NEXTVTX[u]];
    del = -SLACK(i) / 2;
    }
    else del = LAST_D;

    i = u;
    while (i != DUMMYVERTEX) {
    Y[i] += del;
    NEXT_D[i] += del;
    i = NEXTVTX[i];
    }
    if (LINK[v] < 0) {
    LINK[v] = e;
    NEXTPAIR[DUMMYEDGE] = DUMMYEDGE;
    SCAN (v, DELTA);
    return;
    }
    else {
    LINK[v] = e;
    return;
    }
}


/* Scan each vertex in the blossom whose base is x */

SCAN (x, del)
int x, del;

{   int u, del_e;

#ifdef DEBUG
    printf("Scan del=%d x=%d\n",del,x);
#endif

    newbase = BASE[x];
    stopscan = NEXTVTX[LASTVTX[x]];
    while (x != stopscan) {
    Y[x] += del;
    NEXT_D[x] = LAST_D;
    pairpoint = DUMMYEDGE;
    e = A[x];
    while (e != 0) {
        neighbor = END[e];
        u = BASE[neighbor];
        if (LINK[u] < 0) {
        if (LINK[BMATE (u)] < 0 || LASTVTX[u] != u) {
            del_e = SLACK (e);
            if (NEXT_D[neighbor] > del_e) {
            NEXT_D[neighbor] = del_e;
            NEXTEDGE[neighbor] = e;
            }
            }
        }
        else if (u != newbase) {
        INSERT_PAIR();
        }
        e = A[e];
        }
    x = NEXTVTX[x];
    }
    NEXTEDGE[newbase] = NEXTPAIR[DUMMYEDGE];
}

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