hdu-3308-LCIS 线段树

结构里

a 该段最左的数

b该段最有的数

la该段从左开始 向右的最长递增长度

lb该段从右开始 向左的最长递增长度

ll该段的 最长递增长度

len该段的总长度

l 该段左端点

r 该段右端点

然后画图思考下，怎么递归着建树和更新，求区间最大值。。。

#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
#define N 101000

struct node{
int a,b;
int la,lb,ll;
int len;
int l,r;
}tree[3*N];
int p
;
void build(int id,int x,int y)
{
tree[id].l=x;
tree[id].r=y;
tree[id].a=p[x];
tree[id].b=p[y];
tree[id].len=y-x+1;
int t1=id<<1,t2=(id<<1)+1;
if(x==y)
{
tree[id].la=1;
tree[id].lb=1;
tree[id].ll=1;
return ;
}
int mid=(x+y)>>1;
build(t1,x,mid);
build(t2,mid+1,y);
if(tree[t1].len == tree[t1].la && tree[t1].b<tree[t2].a)
tree[id].la=tree[t1].la+tree[t2].la;
else
tree[id].la=tree[t1].la;
if(tree[t2].len==tree[t2].lb && tree[t1].b<tree[t2].a)
tree[id].lb=tree[t2].lb+tree[t1].lb;
else
tree[id].lb=tree[t2].lb;
tree[id].ll=max(tree[t1].ll,tree[t2].ll);
if(tree[t1].b<tree[t2].a)
tree[id].ll=max(tree[id].ll,tree[t1].lb+tree[t2].la);
}
int query(int id,int x,int y)
{
int left=tree[id].l;
int right=tree[id].r;
int mid=(left+right)>>1;
if(x==left && y==right)
return tree[id].ll;
if(y<=mid) return query(id<<1,x,y);
else if(x>=mid+1) return query((id<<1)+1,x,y);
else
{
int t1=query(id<<1,x,mid);
int t2=query((id<<1)+1,mid+1,y);
if(tree[id<<1].b < tree[(id<<1)+1].a)
return max(max(t1,t2),min(tree[id<<1].lb,mid-x+1)+min(tree[(id<<1)+1].la,y-mid));
else
return max(t1,t2);
}
}
void change(int id,int x,int y)
{
int left=tree[id].l;
int right=tree[id].r;
int mid=(left+right)>>1;
if(left==right && left==x)
{
tree[id].a=y;
tree[id].b=y;
return ;
}
int t1=id<<1,t2=(id<<1)+1;
if(x<=mid)
change(id<<1,x,y);
else
change((id<<1)+1,x,y);
if(x==left)
tree[id].a=y;
else if(x==right)
tree[id].b=y;
if(tree[t1].len == tree[t1].la && tree[t1].b<tree[t2].a)
tree[id].la=tree[t1].la+tree[t2].la;
else
tree[id].la=tree[t1].la;
if(tree[t2].len==tree[t2].lb && tree[t1].b<tree[t2].a)
tree[id].lb=tree[t2].lb+tree[t1].lb;
else
tree[id].lb=tree[t2].lb;
tree[id].ll=max(tree[t1].ll,tree[t2].ll);
if(tree[t1].b<tree[t2].a)
tree[id].ll=max(tree[id].ll,tree[t1].lb+tree[t2].la);
}
int main()
{
int t;
scanf("%d",&t);
while(t--)
{
int n,m,i,j,k;
scanf("%d%d",&n,&k);
for(i=1;i<=n;i++)
scanf("%d",&p[i]);
build(1,1,n);
char ch[2];
int h,g;
while(k--)
{
scanf("%s",ch);
if(ch[0]=='Q'){
scanf("%d%d",&g,&h);
g++;
h++;
int ans=query(1,g,h);
printf("%d\n",ans);
}
else if(ch[0]=='U'){
scanf("%d%d",&g,&h);
g++;
change(1,g,h);
}
}
}
}