Hdu1754 I Hate It

The single-point update template of the Line Segment tree calculates the maximum interval.

#include 
 
  #include 
  
   #include 
   
    #include 
    
     #include 
     
      #include #include 
      
       #include 
       
        #include 
        #define inf 0x3f3f3f3f#define eps 1e-6#define ll __int64using namespace std;int n,m,tre[800010];void build(int num,int s,int e){ int a; if(s==e) { scanf("%d",&a); tre[num]=a; return ; } int mid=(s+e)>>1; build(num<<1,s,mid); build(num<<1|1,mid+1,e); tre[num]=max(tre[num<<1],tre[num<<1|1]);}void update(int num,int s,int e,int pos,int val){ if(s==e) { tre[num]=val; return ; } int mid=(s+e)>>1; if(pos<=mid) update(num<<1,s,mid,pos,val); else update(num<<1|1,mid+1,e,pos,val); tre[num]=max(tre[num<<1],tre[num<<1|1]);}int query(int num,int s,int e,int l,int r){ if(l<=s&&e<=r) { return tre[num]; } int mid=(s+e)>>1; if(r<=mid) return query(num<<1,s,mid,l,r); else if(l>mid) return query(num<<1|1,mid+1,e,l,r); else return max(query(num<<1,s,mid,l,mid),query(num<<1|1,mid+1,e,mid+1,r));}int main(){ int a,b; char str[10]; while(~scanf("%d%d",&n,&m)) { build(1,1,n); while(m--) { scanf("%s",&str); if(str[0]=='U') { scanf("%d%d",&a,&b); update(1,1,n,a,b); } else { scanf("%d%d",&a,&b); printf("%d\n",query(1,1,n,a,b)); } } } return 0;}