hdu 1754 I Hate It

// Time 843ms; Memory 6448K

#include<iostream>
#include<cstdio>
#define maxn 1<<19
#define inf 1<<30

using namespace std;

int size,n,sm,al[5010];
struct line
{
int l,r;
int n;
}a[maxn];

void init()
{
int i;
for(n=1;n<size;n<<=1);
for(i=n;i<2*n;i++)
{
a[i].l=a[i].r=i-n+1;
a[i].n=-inf;
}
for(i=n-1;i>0;i--)
{
a[i].l=a[2*i].l;
a[i].r=a[2*i+1].r;
a[i].n=-inf;
}
}
void insert(int i,int x,int m)
{
if(x>=a[i].l && x<=a[i].r && a[i].n<m) a[i].n=m;
if(a[i].l==a[i].r) return;
int mid=(a[i].l+a[i].r)/2;
if(x>mid) insert(2*i+1,x,m);
else insert(2*i,x,m);
}
void find(int x,int y,int i)
{
if(x==a[i].l && y==a[i].r)
{
if(sm<a[i].n)
sm=a[i].n;
return;
}
if(a[i].l==a[i].r) return;
int mid=(a[i].l+a[i].r)/2;
if(x>mid) find(x,y,2*i+1);
else if(y<=mid) find(x,y,2*i);
else
{
find(x,mid,2*i);
find(mid+1,y,2*i+1);
}
}
int main()
{
int j,k,t,x,y,m;
char s;
while(scanf("%d%d",&size,&t)!=EOF)
{
init();
for(j=0;j<size;j++)
{
scanf("%d",&k);
insert(1,j+1,k);
}
k=0;
for(j=0;j<t;j++)
{
scanf(" %c",&s);
if(s=='U')
{
scanf("%d%d",&x,&m);
insert(1,x,m);
}
else
{
scanf("%d%d",&x,&y);
sm=-inf;
find(x,y,1);
al[k++]=sm;
}
}
for(j=0;j<k;j++) printf("%d\n",al[j]);
}
return 0;
}