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 101000struct node{int a,b;int la,lb,ll;int len;int l,r;}tree[3*N];int p[N];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;elsetree[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;elsetree[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));elsereturn 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);elsechange((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;elsetree[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;elsetree[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);}}}}