Section 9.1

省选准备/assets/day10/bzoj1588.cpp

@@ -0,0 +1,151 @@
+#include <cstdio>
+#include <cstdlib>
+static const int arrSize = 40000;
+typedef int valType;
+struct Node
+{
+    valType val;
+    Node *child[2], *father;
+};
+typedef Node *lpNode;
+struct allocator
+{
+private:
+    int i;
+    Node data[arrSize];
+    lpNode pt[arrSize];
+
+public:
+    allocator()
+    {
+        this->i = 0;
+        for (int j = 0; j < arrSize; j++) pt[j] = data + j;
+    }
+    lpNode alloc() { return pt[i++]; }
+    void free(lpNode ptr) { pt[--i] = ptr; }
+} mem;
+void rotate(lpNode x, int direction)
+{
+    lpNode p = x->father;
+    p->child[!direction] = x->child[direction];
+    if (x->child[direction]) x->child[direction]->father = p;
+    x->father = p->father;
+    if (p->father) p->father->child[p != p->father->child[0]] = x;
+    p->father = x;
+    x->child[direction] = p;
+}
+void Splay(lpNode x, lpNode target)
+{
+    lpNode p;
+    target = target->father;
+    while (x->father != target)
+    {
+        p = x->father;
+        if (p->father == target)
+        {
+            rotate(x, x == p->child[0]);
+            break;
+        }
+        else if (x == p->child[0])
+            if (p == p->father->child[0]) {
+                rotate(p, 1);
+                rotate(x, 1);
+            }
+            else
+            {
+                rotate(x, 1);
+                rotate(x, 0);
+            }
+        else if (p == p->father->child[1])
+        {
+            rotate(p, 0);
+            rotate(x, 0);
+        }
+        else
+        {
+            rotate(x, 0);
+            rotate(x, 1);
+        }
+    }
+}
+lpNode max(lpNode x)
+{
+    while (x && x->child[1]) x = x->child[1];
+    return x;
+}
+lpNode min(lpNode x)
+{
+    while (x && x->child[0]) x = x->child[0];
+    return x;
+}
+lpNode find(valType x, lpNode s)
+{
+    lpNode p = s;
+    while (true)
+        if (p == 0)
+            return p;
+        else if (p->val == x)
+        {
+            Splay(p, s);
+            return p;
+        }
+        else
+            p = p->child[x > p->val];
+}
+lpNode pred(valType x, lpNode s) { return max(find(x, s)->child[0]); }
+lpNode succ(valType x, lpNode s) { return min(find(x, s)->child[1]); }
+void ins(valType x, lpNode &s)
+{
+    if (s == 0)
+    {
+        s = mem.alloc();
+        s->val = x;
+    }
+    else
+    {
+        lpNode p = 0, _s = s;
+        while (s)
+        {
+            p = s;
+            s = s->child[x > s->val];
+        }
+        if (p == 0)
+            s->val = x;
+        else
+        {
+            lpNode n = mem.alloc();
+            n->val = x;
+            n->father = p;
+            p->child[x > p->val] = n;
+            s = _s;
+            Splay(n, s);
+            s = n;
+        }
+    }
+}
+valType _min(valType a, valType b) { return (a < b ? a : b); }
+lpNode root = 0;
+int main()
+{
+    int n, tmp, ans = 0;
+    scanf("%d", &n);
+    for (int i = 0; i < n; i++)
+    {
+        scanf("%d", &tmp);
+        ins(tmp, root);
+        if (i == 0)
+            ans += tmp;
+        else
+        {
+            lpNode p = pred(tmp, root), s = succ(tmp, root);
+            if (p == 0)
+                ans += abs(tmp - s->val);
+            else if (s == 0)
+                ans += abs(tmp - p->val);
+            else
+                ans += _min(abs(tmp - s->val), abs(tmp - p->val));
+        }
+    }
+    printf("%d", ans);
+    return 0;
+}

省选准备/省选基础算法.tex

@@ -590,4 +590,7 @@ Manacher 模板题
 \paragraph{做法} 插入之后维护一下堆性质，乱搞搞就好了，递归的方法写起来很容易，并且不易写错。删除的时候就把那个节点转到一条链上，然后删掉它。
 \paragraph{示例代码} 模板题
 \codeinput[\href{http://www.lydsy.com/JudgeOnline/problem.php?id=3224}{BZOJ3224} - 普通平衡树]{assets/day10/Treap.cpp}
+\subsubsection{练习题}
+\paragraph{BZOJ1588 营业额统计} 其实可以用\verb|std::set|水过去。
+\codeinput[\href{http://www.lydsy.com/JudgeOnline/problem.php?id=1588}{BZOJ1588} - 营业额统计]{assets/day10/bzoj1588.cpp}
 \end{document}