hdu1533 going home 二分图最优匹配

二分图最优匹配

#include <iostream>
#include <string.h>
#include <cstdio>

using namespace std;

const int MAXN = 100 + 10;
const int INF = (~0U >> 1);

char temp[MAXN][MAXN];
int c[MAXN][MAXN];
int lx[MAXN], ly[MAXN];
bool visx[MAXN], visy[MAXN];
int match[MAXN];
int row, col;
int numm, numh;

struct Node
{
    int x, y;
}M[MAXN], H[MAXN];

int abs(int x)
{
    return x < 0 ? -x : x;
}

bool dfs(int u)
{
    visx[u] = true;

    for (int i = 0; i < numm; i++)
    {
        if (!visy[i] && lx[u] + ly[i] - c[u][i] == 0)
        {
            visy[i] = true;

            if (match[i] == -1 || dfs(match[i]))
            {
                match[i] = u;
                return true;
            }
        }
    }

    return false;
}

void solve()
{
    memset(ly, 0, sizeof(ly));
    memset(match, -1, sizeof(match));

    for (int i = 0; i < numm; i++)
    {
        lx[i] = c[i][0];
        for (int j = 1; j < numm; j++)
        {
            if (c[i][j] > lx[i])
            {
                lx[i] = c[i][j];
            }
        }
    }

    for (int i = 0; i < numm; i++)
    {
        while (true)
        {
            memset(visx, false, sizeof(visx));
            memset(visy, false, sizeof(visy));

            if (dfs(i))
            {
                break;
            }

            int inc = INF;

            for (int i = 0; i < numm; i++)
            {
                if (visx[i])
                {
                    for (int j = 0; j < numm; j++)
                    {
                        if (!visy[j] && lx[i] + ly[j] - c[i][j] < inc)
                        {
                            inc = lx[i] + ly[j] - c[i][j];
                        }
                    }
                }
            }

            for (int i = 0; i < numm; i++)
            {
                if (visx[i])
                {
                    lx[i] -= inc;
                }
                if (visy[i])
                {
                    ly[i] += inc;
                }
            }
        }
    }

    int ans = 0;

    for (int i = 0; i < numm; i++)
    {
        ans += c[match[i]][i];
    }

    cout << -ans << endl;
}

void input()
{
    while (scanf("%d %d", &row, &col) && (row || col))
    {
        numm = numh = 0;
        for (int i = 0; i < row; i++)
        {
            scanf("%s", temp[i]);

            for (int j = 0; j < col; j++)
            {
                if (temp[i][j] == 'm')
                {
                    M[numm].x = i;
                    M[numm++].y = j;
                }
                else if (temp[i][j] == 'H')
                {
                    H[numh].x = i;
                    H[numh++].y = j;
                }
            }
        }

        for (int i = 0; i < numm; i++)
        {
            for (int j = 0; j < numm; j++)
            {
                c[i][j] = -(abs(M[i].x - H[j].x) + abs(M[i].y - H[j].y));
            }
        }

        solve();
    }
}

int main()
{
    input();
    return 0;
}