### [题解]ZOJ Monthly, February 2011 » ZOJ3475

ZOJ3475.cpp

```#include <queue>
#include <cstdio>
#include <vector>
#include <algorithm>

using namespace std;

const int MAXN = 444;
const int MAXM = 4444;
const int INF = 1000000007;

inline int RE(int i) { return i ^ 1; }

struct Edge {
int v;
int c;
};

struct FlowNetwork {
int n, m, source, sink;
vector<int> e[MAXN];
Edge edge[MAXM * 2];

void init(int n, int source, int sink) {
this->n = n;
this->m = 0;
this->source = source;
this->sink = sink;
for (int i = 0; i < n; ++i) {
e[i].clear();
}
}

void addEdge(int a, int b, int c) {
edge[m].v = b;
edge[m].c = c;
e[a].push_back(m);
edge[m + 1].v = a;
edge[m + 1].c = c;
e[b].push_back(m + 1);
m += 2;
}

// shortest augmenting path
int c[MAXN];		//*
int d[MAXN];		//*
int done[MAXN];		//*
int path[MAXN];		//*
int len;			//*

void _bfs() {
queue<int> q;
fill(c, c + n, 0);
fill(d, d + n, n);	// n->inf
d[sink] = 0;
q.push(sink);
while (!q.empty()) {
int cur = q.front();
++c[d[cur]];
for (size_t i = 0; i < e[cur].size(); ++i) {
int id = e[cur][i];
if (d[edge[id].v] == n && edge[RE(id)].c > 0) {
d[edge[id].v] = d[cur] + 1;
q.push(edge[id].v);
}
}
q.pop();
}
}

void _retreat(int v) {
--c[d[v]];
d[v] = n;	// n->inf
for (size_t i = 0; i < e[v].size(); ++i) {
Edge &arc = edge[e[v][i]];
if (d[v] > d[arc.v] + 1 && arc.c > 0) {
d[v] = d[arc.v] + 1;
done[v] = i;	// ~
}
}
++c[d[v]];
}

int _augment() {
int todo = -1;
int flow = INF;
for (int i = 0; i < len; ++i) {
Edge &arc = edge[e[path[i]][done[path[i]]]];
if (arc.c < flow) {
flow = arc.c;
todo = i;
}
}
for (int i = 0; i < len; ++i) {
int id = e[path[i]][done[path[i]]];
edge[id].c -= flow;
edge[RE(id)].c += flow;
}
len = todo;
return flow;
}

int sap() {
int flow = 0;
_bfs();
fill(done, done + n, 0);
len = 0;
path[0] = source;
while (d1 != n/* && len >= 0*/) {	// n->inf
int back = path[len];
if (back == sink) {
flow += _augment();
} else {
while (done[back] < (int)e[back].size()) {
Edge &arc = edge[e[back][done[back]]];
if (d[arc.v] == d[back] - 1 && arc.c > 0) {
break;
} else {
++done[back];
}
}
if (done[back] == (int)e[back].size()) {
if (c[d[back]] == 1) {
break;	// return;
} else {
_retreat(back);
if (back != source) {	// !!
--len;	// pop
}
}
} else {
path[++len] = edge[e[back][done[back]]].v;	// push
}
}
}
return flow;
}
// end of sap
} fn, _fn;

#define ID(i, j) ((i) * c + (j))
#define S() (r * c)
#define T() (r * c + 1)

int main() {
int n, r, c, f, ans;
int x[10], y[10], z[10];

while (scanf("%d%d", &r, &c) != EOF) {
_fn.init(r * c + 2, S(), T());
for (int i = 0; i <= r; ++i) {
for (int j = 0; j < c; ++j) {
scanf("%d", &f);
_fn.addEdge(i == 0 ? T() : ID(i - 1, j), i == r ? T() : ID(i, j), f);
}
if (i == r) {
break;
}
for (int j = 0; j <= c; ++j) {
scanf("%d", &f);
_fn.addEdge(j == 0 ? T() : ID(i, j - 1), j == c ? T() : ID(i, j), f);
}
}

scanf("%d", &n);
for (int i = 0; i < n; ++i) {
scanf("%d%d%d", &z[i], &x[i], &y[i]);
if (z[i] == 0) {
swap(x[i], x[0]);
swap(y[i], y[0]);
swap(z[i], z[0]);
} else if (z[i] < 0) {
--i;
--n;
}
}

ans = INF;
for (int i = 1; i < (1 << n); i += 2) {
fn = _fn;
f = 0;
for (int j = 0; j < n; ++j) {
if (i & (1 << j)) {
f -= z[j];
}
}
f += fn.sap();
ans = min(ans, f);
}
printf("%d\n", ans);
}

return 0;
}

//Run ID 	Submit Time 	Judge Status 	Problem ID 	Language 	Run Time(ms) 	Run Memory(KB) 	User Name 	Admin
//711 	2011-02-09 22:22:22 	Accepted 	I 	C++ 	40 	344 	watashi@ArcOfDream 	Source
```