HDU 4453 Looploop （splay tree）

Looploop

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<vector>

//对区间操作
#define Key_value ch[ch[root][1]][0]

using namespace std;
const int maxn = 4e5 + 10;
int root, tot1;
int ch[maxn][2], pre[maxn], key[maxn], size[maxn], add[maxn], rev[maxn];
int s[maxn], tot2;
int n, q, k1, k2, pos, a[maxn];

void Update_Add(int r, int v)
{
if(!r) return;
key[r] += v;
add[r] += v;
}

void Update_Rev(int r)
{
if(!r) return;
swap(ch[r][0], ch[r][1]);
rev[r] ^= 1;
}

void PushUp(int r)
{
size[r] = size[ch[r][0]] + size[ch[r][1]] + 1;
}

void PushDown(int r)
{
if(add[r])
{
Update_Add(ch[r][0], add[r]);
Update_Add(ch[r][1], add[r]);
add[r] = 0;
}
if(rev[r])
{
Update_Rev(ch[r][0]);
Update_Rev(ch[r][1]);
rev[r] = 0;
}
}

void NewNode(int &r, int fa, int v)
{
if(tot2) r = s[tot2--];
else r = ++tot1;
ch[r][0] = ch[r][1] = add[r] = 0;
size[r] = 1;
pre[r] = fa;
key[r] = v;
rev[r] = 0;
add[r] = 0;
}

void Build(int &x, int fa, int l, int r)
{
if(l > r) return;
int mid = (l + r) >> 1;
NewNode(x, fa, a[mid]);
Build(ch[x][0], x, l, mid-1);
Build(ch[x][1], x, mid+1, r);
PushUp(x);
}

void Init()
{
pos = 1;
root = tot1 = tot2 = 0;
add[root] = ch[root][0] = ch[root][1] = pre[root] = key[root] = size[root] = 0;
for(int i = 1; i <= n; i++) scanf("%d", &a[i]);
//放两个虚拟节点
NewNode(root, 0, -1);
NewNode(ch[root][1], root, -1);
//建树
Build(Key_value, ch[root][1], 1, n);

PushUp(ch[root][1]);
PushUp(root);
}

void Rotate(int x, int kind)
{
int y = pre[x];
PushDown(y);
PushDown(x);
ch[y][!kind] = ch[x][kind];
pre[ch[x][kind]] = y;
if(pre[y])
ch[pre[y]][ch[pre[y]][1]==y] = x;
pre[x] = pre[y];
ch[x][kind] = y;
pre[y] = x;
PushUp(y);
}

void Splay(int r, int goal)
{
PushDown(r);
while(pre[r] != goal)
{
if(pre[pre[r]] == goal)
{

Rotate(r, ch[pre[r]][0]==r);
}
else
{
int y = pre[r];
int kind = (ch[pre[y]][0]==y);
if(ch[y][kind] == r)
{
Rotate(r, !kind);
Rotate(r, kind);
}
else
{
Rotate(y, kind);
Rotate(r, kind);
}
}
}
PushUp(r);
if(goal == 0) root = r;
}

int Get_Max(int r)
{
PushDown(r);
while(ch[r][1])
{
r = ch[r][1];
PushDown(r);
}
return r;
}

//得到序列第k个元素
int Kth(int r, int k)
{
PushDown(r);
int t = size[ch[r][0]] + 1;
if(k == t) return r;
else if(k < t) return Kth(ch[r][0], k);
else return Kth(ch[r][1], k - t);
}

//将区间[l, r]放到尾部
void MoveLast(int l, int r)
{
if(l > r) return;
//首先将区间[l,r]旋转到root下面，并切割出来。
Splay(Kth(root, l), 0);
Splay(Kth(root, r+2), root);
int rt = Key_value;
Key_value = 0;
PushUp(ch[root][1]);
PushUp(root);
//找到剩余区间中最后一个元素（注意：因为最后有个虚拟节点，所以这里取的是最后的虚拟节点）
Splay(Get_Max(root), 0);
int rtt = root;
root = ch[root][0]; //把这个虚拟节点从原序列中删除
pre[root] = 0;
PushUp(root);
//再找剩余区间中最后一个元素（这个就是真正的序列末元素了），并将区间[l,r]接到其后面
Splay(Get_Max(root), 0);
ch[root][1] = rt;
pre[rt] = root;
PushUp(root);
//把删掉的虚拟节点加上
ch[rtt][0] = root;
pre[root] = rtt;
root = rtt;
pre[root] = 0;
PushUp(root);
}

void Insert(int x)
{
int r;
Splay(Kth(root, pos+1), 0);
Splay(Kth(root, pos+2), root);
NewNode(r, ch[root][1], x);
Key_value = r;
PushUp(ch[root][1]);
PushUp(root);
++n;
}

void erase(int r)
{
if(!r) return;
erase(ch[r][0]);
erase(ch[r][1]);
s[++tot2] = r;
}

void Delete()
{
//这两步将第pos元素转到ch[root][1]下面
Splay(Kth(root, pos), 0);
Splay(Kth(root, pos+2), root);
int r = Key_value;
Key_value = 0;
pre[r] = 0;
erase(r);
PushUp(ch[root][1]);
PushUp(root);
if(pos == n) pos = 1;
--n;
}

void Move(int x)
{
if(x == 1) pos = (pos > 1 ? pos-1 : n);
else pos = (pos < n ? pos+1 : 1);
}

int Query()
{
Splay(Kth(root, pos+1), 0);
return key[root];
}

void Add(int x)
{
MoveLast(1, pos-1);
pos = 1;
int l = pos, r = pos + k2 - 1;
Splay(Kth(root, l), 0);
Splay(Kth(root, r+2), root);
Update_Add(Key_value, x);
}

void Reverse()
{
MoveLast(1, pos-1);
pos = 1;
int l = pos, r = pos + k1 - 1;
Splay(Kth(root, l), 0);
Splay(Kth(root, r+2), root);
Update_Rev(Key_value);
}

int main()
{
int kase = 0;
while(scanf("%d%d%d%d", &n, &q, &k1, &k2) == 4)
{
if(!n && !q && !k1 && !k2) break;
char op[10];
int x;
Init();
printf("Case #%d:\n", ++kase);
for(int i = 1; i <= q; i++)
{
scanf("%s", op);
if(op[0] == 'a')
{
scanf("%d", &x);
Add(x);
}
else if(op[0] == 'r') Reverse();
else if(op[0] == 'i')
{
scanf("%d", &x);
Insert(x);
}
else if(op[0] == 'd') Delete();
else if(op[0] == 'm')
{
scanf("%d", &x);
Move(x);
}
else if(op[0] == 'q') printf("%d\n", Query());

}
}
return 0;
}