hdu1045 Fire Net

http://acm.hdu.edu.cn/showproblem.php?pid=1045

二分图匹配，匈牙利算法(dfs+邻接矩阵)，König定理

需要自己建新图

以前用搜索做过~ 感觉建图好神奇

#include <stdio.h>
#include <string.h>
#define N 10

int n, m;
int map0[N][N], map1[N][N], map2[N][N];
int map[N][N], girl[N], flag[N];

int find(int x)
{
    int i;
    for(i=1; i<=m; i++)
    {
        if(!flag[i] && map[x][i])
        {
            flag[i] = 1;
            if(girl[i]==-1 || find(girl[i]))
            {
                girl[i] = x;
                return 1;
            }
        }
    }
    return 0;
}

int main()
{
    int n0, i, j, sum, count;
    char c;
    while(scanf("%d%*c", &n0), n0)
    {
        //初始化
        memset(map, 0, sizeof(map));
        memset(girl, -1, sizeof(girl));
        for(i=1; i<=n0; i++)
        {
            map0[i][0] = map0[0][i] = 1;
            for(j=1; j<=n0; j++)
            {
                scanf("%c", &c);
                map0[i][j] = c-'.';
            }
            getchar();
        }
        //给每个点编一个新行号
        count = 0;
        for(i=1; i<=n0; i++)
        {
            for(j=1; j<=n0; j++)
            {
                if(map0[i][j-1] && (!map0[i][j]))
                {
                    count ++;
                }
                map1[i][j] = count;
            }
        }
        n = count;
        //给每个点编一个新列号
        count = 0;
        for(j=1; j<=n0; j++)
        {
            for(i=1; i<=n0; i++)
            {
                if(map0[i-1][j] && (!map0[i][j]))
                {
                    count ++;
                }
                map2[i][j] = count;
            }
        }
        m = count;
        //根据新的行列号，建图
        for(i=1; i<=n0; i++)
        {
            for(j=1; j<=n0; j++)
            {
                if(!map0[i][j])
                {
                    map[map1[i][j]] [map2[i][j]] = 1;
                }
            }
        }
        //匈牙利算法
        sum = 0;
        for(i=1; i<=n; i++)
        {
            memset(flag, 0, sizeof(flag));
            sum += find(i);
        }
        printf("%d\n", sum);        
    }
    return 0;
}