Все задачи на 5.10.17 13:00

uts/uts_2017_sum_cpp/4/A.cpp

@@ -0,0 +1,63 @@
+#include <iostream>
+#include <bits/stdc++.h>
+
+using namespace std;
+const int MAXN = 1e6;
+vector<int> tree[MAXN];
+int lel[MAXN];
+int in[MAXN];
+int out[MAXN];
+int timer = 0;
+
+bool is_anc(int a, int b) {
+    return (in[a] <= in[b]) && (out[b] <= out[a]);
+}
+
+void dfs(int v, int p, int h) {
+    lel[v] = h;
+    in[v] = timer++;
+    for (int u : tree[v]) {
+        if (u == p) {
+            continue;
+        }
+        dfs(u, v, h + 1);
+    }
+    out[v] = timer++;
+}
+
+int main() {
+    //assert(freopen("../4/A.txt", "r", stdin));
+    ios_base::sync_with_stdio(false);
+    cin.tie(0);
+
+    int n, m, k;
+
+    cin >> n >> m >> k;
+
+    for (int i = 1; i < n; i++) {
+        int v;
+        cin >> v;
+        tree[i].push_back(--v);
+        tree[v].push_back(i);
+    }
+
+    dfs(0, -1, 0);
+
+    for (int i = 0; i < m; i++) {
+        int vi, ui;
+        cin >> vi >> ui;
+        --vi;
+        --ui;
+
+        if (!is_anc(vi, ui)){
+            cout << "no\n";
+            continue;
+        }
+
+        if (lel[ui] - lel[vi] > k) {
+            cout << "no\n";
+        } else {
+            cout << "yes\n";
+        }
+    }
+}