poj2195 Going Home 最小权值匹配

题意：

思路：

代码：

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <iostream>
#include <vector>

#define INF 0x3f3f3f3f

using namespace std;

struct Point{
int x, y;
}man[105], house[105];

int n, m;
int mcnt, hcnt;
int edges[105][105];
int A[105], B[105];
int mat[105];
bool visA[105], visB[105];
int d;

void init() {
for (int i = 1; i <= mcnt; i++)
for (int j = 1; j <= hcnt; j++)
edges[i][j] = abs(man[i].x - house[j].x) + abs(man[i].y - house[j].y);

memset(A, 0x3f, sizeof(A));
memset(B, 0, sizeof(B));
for (int i = 1; i <= mcnt; i++)
for (int j = 1; j <= hcnt; j++)
A[i] = min(A[i], edges[i][j]);
}

bool dfs(int i) {
visA[i] = 1;
for (int j = 1; j <= hcnt; j++) {
if (!visB[j] && edges[i][j]) {
int t = edges[i][j] - A[i] - B[j];
if (!t) {
visB[j] = 1;
if (!mat[j] || dfs(mat[j])) {
mat[j] = i;
return true;
}
} else d = min(d, t);
}
}
return false;
}

int match() {
memset(mat, 0, sizeof(mat));
for (int i = 1; i <= mcnt; i++) {
while (true) {
memset(visA, 0, sizeof(visA));
memset(visB, 0, sizeof(visB));
d = INF;
if (dfs(i)) break;
for (int j = 1; j <= mcnt; j++) {
if (visA[j]) A[j] += d;
if (visB[j]) B[j] -= d;
}
}
}
int ans = 0;
for (int i = 1; i <= hcnt; i++)
ans += edges[mat[i]][i];
return ans;
}

int main() {
while (~scanf("%d %d", &n, &m) && n && m) {
char c;
mcnt = hcnt = 0;
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
cin >> c;
if (c == 'm') {
mcnt++;
man[mcnt].x = i;
man[mcnt].y = j;
} else if (c == 'H') {
hcnt++;
house[hcnt].x = i;
house[hcnt].y = j;
}
}
}
init();
int ans = match();
printf("%d\n", ans);
}
return 0;
}