Problem
给你n个数A1~An，每次将i插入第Ai位后，最后输出每次插入后这个数列的最长上升子序列
Solution
这道题非常的妙。首先如果新加入的这个数构成了最长上升子序列，由于在它插入之前都是比它小的数，所以就是最后这个序列这个位置的最长上升子序列。
如果不是最长的，只需要和前面那个数插入构成的最长上升子序列长度取max。
构造最后的序列长度可以用Treap维护。
Notice
插入点时，不用记录是第几个数，因为Treap新建节点的顺序就是插入的顺序。
Code
非旋转Treap
#include<cmath>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
#define sqz main
#define ll long long
#define reg register int
#define rep(i, a, b) for (reg i = a; i <= b; i++)
#define per(i, a, b) for (reg i = a; i >= b; i--)
#define travel(i, u) for (reg i = head[u]; i; i = edge[i].next)
const int INF = 1e9, N = 100000;
const double eps = 1e-6, phi = acos(-1.0);
ll mod(ll a, ll b) {if (a >= b || a < 0) a %= b; if (a < 0) a += b; return a;}
ll read(){ ll x = 0; int zf = 1; char ch; while (ch != '-' && (ch < '0' || ch > '9')) ch = getchar();
if (ch == '-') zf = -1, ch = getchar(); while (ch >= '0' && ch <= '9') x = x * 10 + ch - '0', ch = getchar(); return x * zf;}
void write(ll y) { if (y < 0) putchar('-'), y = -y; if (y > 9) write(y / 10); putchar(y % 10 + '0');}
int point = 0, root, f[N + 5], g[N + 5], T[N + 5], now = 0;
struct node
{
int Val[N + 5], Level[N + 5], Size[N + 5], Son[2][N + 5];
inline void up(int u)
{
Size[u] = Size[Son[0][u]] + Size[Son[1][u]] + 1;
}
int Newnode(int v)
{
int u = ++point;
Val[u] = v, Level[u] = rand();
Son[0][u] = Son[1][u] = 0, Size[u] = 1;
return u;
}
int Merge(int X, int Y)
{
if (X * Y == 0) return X + Y;
if (Level[X] < Level[Y])
{
Son[1][X] = Merge(Son[1][X], Y);
up(X); return X;
}
else
{
Son[0][Y] = Merge(X, Son[0][Y]);
up(Y); return Y;
}
}
void Split(int u, int t, int &x, int &y)
{
if (!u)
{
x = y = 0;
return;
}
if (Size[Son[0][u]] < t) x = u, Split(Son[1][u], t - Size[Son[0][u]] - 1, Son[1][u], y);
else y = u, Split(Son[0][u], t, x, Son[0][u]);
up(u);
}
void Build(int l, int r)
{
int last, u, s[N + 5], top = 0;
rep(i, l, r)
{
int u = Newnode(T[i]);
last = 0;
while (top && Level[s[top]] > Level[u])
{
up(s[top]);
last = s[top];
s[top--] = 0;
}
if (top) Son[1][s[top]] = u;
Son[0][u] = last;
s[++top] = u;
}
while (top) up(s[top--]);
root = s[1];
}
int Find_rank(int v)
{
int x, y, t;
Split(root, v - 1, x, y);
t = Size[x];
root = Merge(x, y);
return t + 1;
}
int Find_num(int u, int v)
{
if (!u) return 0;
if (v <= Size[Son[0][u]]) return Find_num(Son[0][u], v);
else if (v <= Size[Son[0][u]] + 1) return u;
else return Find_num(Son[1][u], v - Size[Son[0][u]] - 1);
}
void Insert(int v)
{
int t = Newnode(v), x, y;
Split(root, v, x, y);
root = Merge(Merge(x, t), y);
}
void Out(int u)
{
if (!u) return;
Out(Son[0][u]);
T[++now] = u;
Out(Son[1][u]);
}
}Treap;
int sqz()
{
int n = read();
rep(i, 1, n)
{
int x = read();
Treap.Insert(x);
}
Treap.Out(root);
g[0] = -1, f[0] = 1;
int len = 0;
rep(i, 1, n)
{
int t = lower_bound(g, g + len + 1, T[i]) - g;
f[T[i]] = t;
if (t == len + 1) g[++len] = T[i];
else g[t] = T[i];
}
rep(i, 1, n)
{
f[i] = max(f[i - 1], f[i]);
printf("%d
", f[i]);
}
return 0;
}
旋转Treap
#include<cmath>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
#define sqz main
#define ll long long
#define reg register int
#define rep(i, a, b) for (reg i = a; i <= b; i++)
#define per(i, a, b) for (reg i = a; i >= b; i--)
#define travel(i, u) for (reg i = head[u]; i; i = edge[i].next)
const int INF = 1e9, N = 100000;
const double eps = 1e-6, phi = acos(-1.0);
ll mod(ll a, ll b) {if (a >= b || a < 0) a %= b; if (a < 0) a += b; return a;}
ll read(){ ll x = 0; int zf = 1; char ch; while (ch != '-' && (ch < '0' || ch > '9')) ch = getchar();
if (ch == '-') zf = -1, ch = getchar(); while (ch >= '0' && ch <= '9') x = x * 10 + ch - '0', ch = getchar(); return x * zf;}
void write(ll y) { if (y < 0) putchar('-'), y = -y; if (y > 9) write(y / 10); putchar(y % 10 + '0');}
int point = 0, root, f[N + 5], g[N + 5], T[N + 5], now = 0;
struct node
{
int Val[N + 5], Level[N + 5], Size[N + 5], Son[2][N + 5];
inline void up(int u)
{
Size[u] = Size[Son[0][u]] + Size[Son[1][u]] + 1;
}
inline void Newnode(int &u, int v)
{
u = ++point;
Level[u] = rand(), Val[u] = v;
Size[u] = 1, Son[0][u] = Son[1][u] = 0;
}
inline void Lturn(int &x)
{
int y = Son[1][x]; Son[1][x] = Son[0][y], Son[0][y] = x;
Size[y] = Size[x]; up(x); x = y;
}
inline void Rturn(int &x)
{
int y = Son[0][x]; Son[0][x] = Son[1][y], Son[1][y] = x;
Size[y] = Size[x]; up(x); x = y;
}
void Insert(int &u, int t)
{
if (u == 0)
{
Newnode(u, t);
return;
}
Size[u]++;
if (Size[Son[0][u]] >= t)
{
Insert(Son[0][u], t);
if (Level[Son[0][u]] < Level[u]) Rturn(u);
}
else
{
Insert(Son[1][u], t - Size[Son[0][u]] - 1);
if (Level[Son[1][u]] < Level[u]) Lturn(u);
}
}
int Find_num(int u, int t)
{
if (!u) return 0;
if (t <= Size[Son[0][u]]) return Find_num(Son[0][u], t);
else if (t <= Size[Son[0][u]] + 1) return Val[u];
else return Find_num(Son[1][u], t - Size[Son[0][u]] - 1);
}
void Out(int u)
{
if (!u) return;
Out(Son[0][u]);
T[++now] = u;
Out(Son[1][u]);
}
}Treap;
int sqz()
{
int n = read();
rep(i, 1, n)
{
int x = read();
Treap.Insert(root, x);
}
Treap.Out(root);
g[0] = -1, f[0] = 1;
int len = 0;
rep(i, 1, n)
{
int t = lower_bound(g, g + len + 1, T[i]) - g;
f[T[i]] = t;
if (t == len + 1) g[++len] = T[i];
else g[t] = T[i];
}
rep(i, 1, n)
{
f[i] = max(f[i - 1], f[i]);
printf("%d
", f[i]);
}
return 0;
}