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59 lines
1.3 KiB
59 lines
1.3 KiB
#include <bits/stdc++.h>
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using namespace std;
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const int N = 2010, M = 1000010;
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int n, m;
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int d[N];
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int st[N];
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int e[M], h[N], idx, w[M], ne[M];
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void add(int a, int b, int c) {
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e[idx] = b, ne[idx] = h[a], w[idx] = c, h[a] = idx++;
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}
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int dfs(int u) {
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if (~d[u]) return d[u]; // 记忆化搜索
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d[u] = 1; // 最少是一级
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for (int i = h[u]; ~i; i = ne[i]) {
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int j = e[i];
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d[u] = max(d[u], dfs(j) + w[i]);
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}
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return d[u];
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}
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int main() {
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#ifndef ONLINE_JUDGE
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freopen("456.in", "r", stdin);
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#endif
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ios::sync_with_stdio(false), cin.tie(0);
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cin >> n >> m;
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memset(h, -1, sizeof h);
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for (int i = 1; i <= m; i++) {
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memset(st, 0, sizeof st);
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int k;
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cin >> k;
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int S = n, T = 1;
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for (int j = 1; j <= k; j++) {
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int x;
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cin >> x;
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S = min(S, x);
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T = max(T, x);
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st[x] = 1;
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}
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for (int j = S; j <= T; j++)
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if (st[j])
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add(n + i, j, 1);
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else
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add(j, n + i, 0);
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}
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int res = 0;
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memset(d, -1, sizeof d);
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for (int i = 1; i <= n; i++) res = max(res, dfs(i));
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printf("%d\n", res);
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return 0;
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} |