1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
| #include <iostream>
#include <cstdio>
#include <queue>
#include <set>
#include <climits>
#define inf INT_MAX
using namespace std;
const int N = 410, M = 1e5 + 10;
bool vis[N];
set <int> ans;
int n, m, st, ed, d[N], cur[N];
int idx = -1, hd[N], nxt[M], edg[M], wt[M];
bool bfs()
{
for (int i = 1; i <= n << 1; i++)
d[i] = -1;
d[st] = 0;
cur[st] = hd[st];
queue <int> q;
q.push(st);
while (!q.empty())
{
int t = q.front();
q.pop();
for (int i = hd[t]; ~i; i = nxt[i])
if (d[edg[i]] == -1 && wt[i])
{
cur[edg[i]] = hd[edg[i]];
d[edg[i]] = d[t] + 1;
if (edg[i] == ed)
return true;
q.push(edg[i]);
}
}
return false;
}
int exploit(int x, int limit)
{
if (x == ed)
return limit;
int res = 0;
for (int i = cur[x]; ~i && res < limit; i = nxt[i])
{
cur[x] = i;
if (d[edg[i]] == d[x] + 1 && wt[i])
{
int t = exploit(edg[i], min(wt[i], limit - res));
if (!t)
d[edg[i]] = -1;
wt[i] -= t;
wt[i ^ 1] += t;
res += t;
}
}
return res;
}
int dinic()
{
int res = 0, flow;
while (bfs())
while (flow = exploit(st, inf))
res += flow;
return res;
}
void add(int a, int b, int c)
{
nxt[++idx] = hd[a];
hd[a] = idx;
edg[idx] = b;
wt[idx] = c;
}
void dfs(int x)
{
vis[x] = true;
for (int i = hd[x]; ~i; i = nxt[i])
if (wt[i] && !vis[edg[i]])
dfs(edg[i]);
}
int main()
{
cin >> n >> m >> st >> ed;
ed += n;
for (int i = 1; i <= n << 1; i++)
hd[i] = -1;
for (int i = 1, a; i <= n; i++)
{
cin >> a;
add(i, i + n, a);
add(i + n, i, 0);
}
for (int i = 1, a, b; i <= m; i++)
{
cin >> a >> b;
add(a + n, b, inf);
add(b, a + n, 0);
add(b + n, a, inf);
add(a, b + n, 0);
}
dinic();
dfs(st);
for (int i = 0; i <= idx; i += 2)
if (vis[edg[i ^ 1]] && !vis[edg[i]])
ans.insert(edg[i ^ 1]);
for (set <int> :: iterator i = ans.begin(); i != ans.end(); i++)
cout << *i << ' ';
return 0;
}
|