Init

ACMOJ-1040.hpp

@@ -0,0 +1,37 @@
+#pragma once
+#ifndef __PROTECTOR_ACMOJ_1040__
+#define __PROTECTOR_ACMOJ_1040__
+#include <functional>
+#include <random>
+typedef bool (*Comparator)(const int &, const int &);
+std::mt19937 rnd(std::random_device{}());
+void nth_element(int *first, int *nth, int *last,
+                 Comparator comp) {
+  if (nth == last) return;
+  while (last - first > 1) {
+    int *p = first, *q = last - 1, *i = first, *j = last - 1;
+    int pivot = *(first + rnd() % (last - first));
+    while (i < j) {
+      while (comp(*i, pivot)) ++i;
+      while (comp(pivot, *j)) --j;
+      if (i <= j) {
+        std::swap(*i, *j);
+        ++i;
+        --j;
+      }
+    }
+    if (nth <= j)
+      last = j + 1;
+    else
+      first = i;
+  }
+}
+void sort(int *first, int *last,
+          Comparator comp) {
+  if (last - first <= 1) return;
+  int *mid = first + (last - first) / 2;
+  nth_element(first, mid, last, comp);
+  sort(first, mid, comp);
+  sort(mid, last, comp);
+}
+#endif