算法-穩定匹配

蓋爾沙普利算法，可以用來解決徵婚交友的穩定匹配問題。

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

#define MALE_NUM    (3)
#define FEMALE_NUM    (MALE_NUM)
/**
male           female
a(edf)         d(abc)
b(efd)         e(cba)
c(fed)         f(bac)
find stable match
*/
#define NO_MATCH_IDX    (0xff)
struct partner
{
    char name[64];
    int mate;
    int prefer[3];
    int matched;
};

struct partner males[3] =
{
    {"a", NO_MATCH_IDX, {1,0,2}, 0},
    {"b", NO_MATCH_IDX, {1,2,0}, 0},
    {"c", NO_MATCH_IDX, {2,1,0}, 0},
};

struct partner females[3] =
{
    {"d", NO_MATCH_IDX, {0,1,2}, 0},
    {"e", NO_MATCH_IDX, {2,1,0}, 0},
    {"f", NO_MATCH_IDX, {1,0,2}, 0},
};

int girl_has_mate(int girl)
{
    return females[girl].matched;
}

void print_match()
{
    int i = 0;
    for (i = 0; i < FEMALE_NUM; i++)
    {
        if (girl_has_mate(i))
        {
            printf("%s<--->%s\n", females[i].name, males[females[i].mate].name);
        }
    }
}

int get_girl_prefer_degree(int girl, int boy)
{
    int i = 0;
    int degree = -1;
    for (i = 0; i < MALE_NUM; i++)
    {
        if (females[girl].prefer[i] == boy)
        {
            degree = i;
        }
    }
    return degree;
}

int girl_prefer_this_boy(int girl, int boy)
{
    int prefer = 0;
    int mate_degree = get_girl_prefer_degree(girl, females[girl].mate);
    int boy_degree = get_girl_prefer_degree(girl, boy);
    if (boy_degree < mate_degree)
    {
        prefer = 1;
    }
    return prefer;
}


int male_select(int boy, int girl)
{
    int i = girl;

    if (girl_has_mate(i))
    {
        if (girl_prefer_this_boy(i, boy))
        {
            males[boy].mate = i;
            males[boy].matched = 1;

            /**girl's mate is free*/
            males[females[i].mate].matched = 0;
            males[females[i].mate].mate = NO_MATCH_IDX;

            /**girl select new mate*/
            females[i].mate = boy;
            females[i].matched = 1;
        }
    }
    else
    {
        males[boy].mate = i;
        males[boy].matched = 1;
        females[i].mate = boy;
        females[i].matched = 1;
    }
    return 0;
}

int male_match(int boy)
{
    int i = 0;
    for (i = 0; i < FEMALE_NUM; i++)
    {
        int girl = males[boy].prefer[i];
        male_select(boy, girl);
        if (males[boy].matched)
        {
            break;
        }
    }
    return 0;
}

int find_unmatched()
{
    int find_idx = NO_MATCH_IDX;
    int i = 0;
    for (i = 0; i < MALE_NUM; i++)
    {
        if (males[i].matched == 0)
        {
            find_idx = i;
            break;
        }
    }
    return find_idx;
}

int gale_sap_male_first()
{
    int boy = 0;
    do
    {
        male_match(boy);
        boy = find_unmatched();

    }while(boy != NO_MATCH_IDX);
    print_match();
    return 0;
}

int main()
{
    gale_sap_male_first();
    getchar();
    return 0;
}