update

poj/2528.mayors-posters/main.cc

@@ -0,0 +1,96 @@
+#include <algorithm>
+#include <cstdio>
+#include <cstring>
+
+using namespace std;
+
+const int N = 10000;
+const int L = 10000000;
+
+int id[2 * N];
+int hash[L + 1];
+
+struct Post {
+  int l;
+  int r;
+};
+
+Post poster[N];
+
+struct TNode {
+  bool val;
+  int beg;
+  int end;
+  TNode *l;
+  TNode *r;
+  int mid() { return beg + (end - beg) / 2; }
+};
+
+TNode tree[8 * N]; // May be 2 * len(id) of intervals, so 2 * 2 * len(id)
+int tid;
+
+TNode *build_tree(TNode *root, int beg, int end) {
+  root->beg = beg;
+  root->end = end;
+  root->val = false;
+  if (beg != end) {
+    root->l = build_tree(&tree[tid++], beg, root->mid());
+    root->r = build_tree(&tree[tid++], root->mid() + 1, end);
+  }
+  return root;
+}
+
+bool query(TNode *root, int beg, int end) {
+  if (root->val) return false;
+  if (root->beg == beg && root->end == end) {
+    return root->val = true;
+    return true;
+  }
+  bool res;
+  if (root->mid() < beg) {
+    res = query(root->r, beg, end);
+  } else if (end <= root->mid()) {
+    res = query(root->l, beg, end);
+  } else {
+    // Do NOT use the short cut operator!
+    bool b1 = query(root->l, beg, root->mid());
+    bool b2 = query(root->r, root->mid() + 1, end);
+    res = b1 || b2;
+  }
+  if (root->l->val && root->r->val) root->val = true;
+  return res;
+}
+
+int main() {
+  int c, n;
+  scanf("%d", &c);
+  while (c--) {
+    scanf("%d", &n);
+    int k = 0;
+    for (int i = 0; i < n; i++) {
+      scanf("%d %d", &poster[i].l, &poster[i].r);
+      id[k++] = poster[i].l;
+      id[k++] = poster[i].r;
+    }
+    sort(id, id + k);
+    k = unique(id, id + k) - id;
+    int intervals = 0;
+    for (int i = 0; i < k; i++) {
+      hash[id[i]] = intervals;
+      if (i < k - 1) {
+        if (id[i] + 1 == id[i + 1])
+          intervals++;
+        else // !!Really important
+          intervals += 2;
+      }
+    }
+    tid = 0;
+    TNode *root = &tree[tid++];
+    build_tree(root, 0, intervals);
+    int cnt = 0;
+    for (int i = n - 1; 0 <= i; i--)
+      if (query(root, hash[poster[i].l], hash[poster[i].r])) cnt++;
+    printf("%d\n", cnt);
+  }
+  return 0;
+}