oiClass-puji P1278-树和数tree

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#include <iostream>
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using namespace std;
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const int N = 1e5 + 5;
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int n, m, a[N], ans;
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int g[N][2];
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void dfs(const int &u) {
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    for (int i = 0; i < 2; ++i) {
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        int v = g[u][i];
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        if (!g[u][i]) continue;
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        if (a[v] <= a[u]) {  // 需要括号
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            ++ans;
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        }
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        if (a[v] == a[u] && !i) {  // 可以省略
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            --ans;
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        }
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        dfs(v);
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    }
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}
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int main() {
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    ios::sync_with_stdio(false);
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    cin.tie(nullptr), cout.tie(nullptr);
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    cin >> n >> m;
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    for (int i = 1; i <= n; ++i) {
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        int l, r, x;
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        cin >> l >> r >> x;
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        g[i][0] = l;
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        g[i][1] = r;
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        a[i] = x;
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    }
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    dfs(1);
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    cout << ans;
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}