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73 lines
2.0 KiB
C++
73 lines
2.0 KiB
C++
#include <cstdio>
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#include <cstring>
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inline int min(int a, int b) { return a < b ? a : b; }
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const int maxn = 210;
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int head[maxn], from[maxn << 1], to[maxn << 1], cap[maxn << 1], next[maxn << 1], ecnt, m, n;
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int d[maxn], que[maxn], cur[maxn], num[maxn], fa[maxn];
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inline void addEdge(int f, int t, int c)
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{
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next[ecnt] = head[f];
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head[f] = ecnt;
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from[ecnt] = f;
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to[ecnt] = t;
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cap[ecnt] = c;
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ecnt++;
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}
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int ISAP(int s, int e)
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{
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int flow = 0;
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int h = 0, t = 0, x;
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for (int i = 1; i <= n; i++) d[i] = n;
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d[que[t++] = e] = 0;
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while (h != t) for (int i = head[x = que[h++]]; i; i = next[i])
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if (cap[i ^ 1] > 0 && d[to[i]] > d[x] + 1)
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d[que[t++] = to[i]] = d[x] + 1;
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memset(num, 0, sizeof(num));
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for (int i = 1; i <= n; i++) num[d[i]]++, cur[i] = head[i];
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x = s;
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while (d[s] < n)
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{
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if (x == e)
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{
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int curFlow = 0x3f3f3f3f;
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for (x = e; x != s; x = from[fa[x]])
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curFlow = min(curFlow, cap[fa[x]]);
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for (x = e; x != s; x = from[fa[x]])
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cap[fa[x]] -= curFlow, cap[fa[x] ^ 1] += curFlow;
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flow += curFlow;
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x = s;
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}
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bool needRetreat = true;
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for (int i = cur[x]; needRetreat && ~i; i = next[i])
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if (cap[i] && d[to[i]] == d[x] - 1)
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needRetreat = false, cur[x] = i, fa[x = to[i]] = i;
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if (needRetreat)
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{
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int mn = n - 1;
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for (int i = head[x]; ~i; i = next[i])
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if (cap[i]) mn = min(mn, d[to[i]]);
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if (--num[d[x]] == 0) break;
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num[d[x] = mn + 1]++;
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cur[x] = head[x];
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if (x != s) x = from[fa[x]];
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}
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}
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return flow;
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}
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int main()
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{
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while (~scanf("%d%d", &m, &n))
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{
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memset(head, -1, sizeof(head));
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ecnt = 0;
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for (int i = 0, x, y, z; i < m; i++)
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{
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scanf("%d%d%d", &x, &y, &z);
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addEdge(x, y, z);
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addEdge(y, x, 0);
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}
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printf("%d\n", ISAP(1, n));
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}
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return 0;
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}
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