嘟嘟嘟
费用流水题。
从源点向每一个人连一条容量为1，费用为0的边；从每一个人向每一栋房子连一条容量为1，费用为两点欧几里得距离的边；从每一栋房子向汇点连一条容量为1，费用为0的边。
跑最小费用最大流即可。
祭写(spfa)时又忘了弹栈后把标记数组清空。
#include<cstdio>
#include<iostream>
#include<cmath>
#include<algorithm>
#include<cstring>
#include<cstdlib>
#include<cctype>
#include<vector>
#include<stack>
#include<queue>
using namespace std;
#define enter puts("")
#define space putchar(' ')
#define Mem(a, x) memset(a, x, sizeof(a))
#define rg register
typedef long long ll;
typedef double db;
const int INF = 0x3f3f3f3f;
const db eps = 1e-8;
const int maxn = 105;
const int maxe = 5e6 + 5;
inline ll read()
{
ll ans = 0;
char ch = getchar(), last = ' ';
while(!isdigit(ch)) last = ch, ch = getchar();
while(isdigit(ch)) ans = (ans << 1) + (ans << 3) + ch - '0', ch = getchar();
if(last == '-') ans = -ans;
return ans;
}
inline void write(ll x)
{
if(x < 0) x = -x, putchar('-');
if(x >= 10) write(x / 10);
putchar(x % 10 + '0');
}
int n, m, s, t;
char a[maxn][maxn];
struct Edge
{
int nxt, from, to, cap, c;
}e[maxe];
int head[maxn * maxn], ecnt = -1;
void addEdge(int x, int y, int w, int c)
{
e[++ecnt] = (Edge){head[x], x, y, w, c};
head[x] = ecnt;
e[++ecnt] = (Edge){head[y], y, x, 0, -c};
head[y] = ecnt;
}
int num(int i, int j)
{
return (i - 1) * m + j;
}
struct Node
{
int x, y;
}h[maxn * maxn];
int cnt = 0;
void build(int x, int y)
{
addEdge(s, num(x, y), 1, 0);
for(int i = 1; i <= cnt; ++i)
addEdge(num(x, y), num(h[i].x, h[i].y), 1, abs(x - h[i].x) + abs(y - h[i].y));
}
bool in[maxn * maxn];
int dis[maxn * maxn], pre[maxn * maxn], flow[maxn * maxn];
bool spfa()
{
Mem(in, 0); Mem(dis, 0x3f);
queue<int> q; q.push(s);
in[s] = 1; dis[s] = 0; flow[s] = INF;
while(!q.empty())
{
int now = q.front(); q.pop(); in[now] = 0;
for(int i = head[now], v; i != -1; i = e[i].nxt)
{
v = e[i].to;
if(e[i].cap && dis[now] + e[i].c < dis[v])
{
dis[v] = dis[now] + e[i].c;
pre[v] = i;
flow[v] = min(flow[now], e[i].cap);
if(!in[v]) in[v] = 1, q.push(v);
}
}
}
return dis[t] != INF;
}
int minCost = 0;
void update()
{
int x = t;
while(x != s)
{
int i = pre[x];
e[i].cap -= flow[t];
e[i ^ 1].cap += flow[t];
x = e[i].from;
}
minCost += flow[t] * dis[t];
}
void MCMF()
{
while(spfa()) update();
}
void init()
{
Mem(head, -1); ecnt = -1;
minCost = 0;
}
int main()
{
while(scanf("%d%d", &n, &m) != EOF && n && m)
{
init();
s = 0; t = n * m + 1;
for(int i = 1; i <= n; ++i) scanf("%s", a[i] + 1);
for(int i = 1; i <= n; ++i)
for(int j = 1; j <= m; ++j)
if(a[i][j] == 'H') addEdge(num(i, j), t, 1, 0), h[++cnt] = (Node){i, j};
for(int i = 1; i <= n; ++i)
for(int j = 1; j <= m; ++j)
if(a[i][j] == 'm') build(i, j);
MCMF();
write(minCost), enter;
}
return 0;
}