Created
September 16, 2013 08:28
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HDU 2426 Interesting Housing Problem
http://acm.hdu.edu.cn/showproblem.php?pid=2426
最小费用最大流
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#include <cstdio> | |
#include <cstring> | |
#include <algorithm> | |
#include <iostream> | |
#include <vector> | |
#include <queue> | |
using namespace std; | |
#define maxn 2110 | |
#define maxm 2000001 | |
const int inf = 0x3f3f3f3f; | |
int nn, m, e; | |
struct Nod { | |
int b, nxt; | |
int cap, cst; | |
void init(int b, int nxt, int cap,int cst) { | |
this->b = b; | |
this->nxt = nxt; | |
this->cap = cap; | |
this->cst = cst; | |
} | |
}; | |
struct MinCost { | |
int E[maxn]; int n; | |
Nod buf[maxm*2]; int len; | |
int p[maxn]; | |
void init(int n) { | |
this->n = n; | |
memset(E, 255, sizeof(E)); | |
len = 0; | |
} | |
void addCap(int a, int b, int cap, int cst) { | |
buf[len].init(b, E[a], cap, cst); E[a] = len ++; | |
buf[len].init(a, E[b], 0, -cst); E[b] = len ++; | |
} | |
bool spfa(int source, int sink) { | |
static queue<int> q; | |
static int d[maxn]; | |
memset(d, 63, sizeof(d)); | |
memset(p, 255, sizeof(p)); | |
d[source] = 0; | |
q.push(source); | |
int u, v; | |
while(!q.empty()) { | |
u = q.front(); | |
q.pop(); | |
for(int i = E[u]; i != -1; i = buf[i].nxt) { | |
v = buf[i].b; | |
if(buf[i].cap>0 && d[u]+buf[i].cst<d[v]) { | |
d[v] = d[u]+buf[i].cst; | |
p[v] = i; | |
q.push(v); | |
} | |
} | |
} | |
return d[sink] != inf; | |
} | |
int solve(int source, int sink) { | |
int minCost = 0,maxFlow = 0;//需要maxFlow的话,想办法返回 | |
while(spfa(source, sink)) { | |
int neck = inf; | |
for(int t=p[sink]; t != -1; t = p[ buf[t^1].b ])//buf[t^1].b是父节点 | |
neck = min(neck, buf[t].cap); | |
maxFlow += neck; | |
for(int t = p[sink]; t != -1; t = p[ buf[t^1].b ]) { | |
buf[t].cap -= neck; | |
buf[t^1].cap += neck; | |
minCost += buf[t].cst * neck; | |
} | |
} | |
//printf("%d\n", maxFlow); | |
if (maxFlow != nn) | |
return 1; | |
return minCost; | |
} | |
} mf; | |
void work() { | |
int s = 0, t = nn + m + 1; | |
mf.init(t); | |
for (int i = 0; i < e; i++) { | |
int a, b, c; | |
scanf("%d %d %d", &a, &b, &c); | |
a++; b++; | |
if (c >= 0) | |
mf.addCap(a, b+nn, 1, -c); | |
} | |
for (int i = 1; i <= nn; i++) | |
mf.addCap(s, i, 1, 0); | |
for (int i = 1; i <= m; i++) | |
mf.addCap(i+nn, t, 1, 0); | |
printf("%d\n", -mf.solve(s, t)); | |
} | |
int main() { | |
int cas = 1; | |
while (scanf("%d %d %d", &nn, &m, &e) != EOF) { | |
printf("Case %d: ", cas++); | |
work(); | |
} | |
return 0; | |
} |
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