uva 1400 - "Ray, Pass me the dishes!"

又是一道线段树区间更新的题；

 #include<cstdio>
 #include<algorithm>
 #include<cstring>
 #define ll long long
 #define maxn 500005
 using namespace std;
 ll sum[maxn];
 struct tree
 {
     int l,r;
     int ml,mr;
     int pre,suf;
     tree *left,*right;
 } tr[maxn*];

 int trcount;

 void build(tree *root,int l,int r)
 {
     root->l=l;
     root->r=r;
     if(l==r)
     {
         root->ml=l;
         root->mr=r;
         root->pre=l;
         root->suf=r;
         return;
     }
     trcount++;
     root->left=tr+trcount;
     trcount++;
     root->right=tr+trcount;
     int mid=(l+r)/;
     build(root->left,l,mid);
     build(root->right,mid+,r);

     //update the pre
     if((sum[root->left->pre]-sum[root->l-])>=(sum[root->right->pre]-sum[root->l-]))
         root->pre=root->left->pre;
     else root->pre=root->right->pre;
     //update the suf
     if((sum[root->r]-sum[root->left->suf-])>=(sum[root->r]-sum[root->right->suf-]))
         root->suf=root->left->suf;
     else root->suf=root->right->suf;
     //update the max
     if((sum[root->left->mr]-sum[root->left->ml-])>=(sum[root->right->mr]-sum[root->right->ml-]))
     {
         root->ml=root->left->ml;
         root->mr=root->left->mr;
     }
     else
     {
         root->mr=root->right->mr;
         root->ml=root->right->ml;
     }
     //update the max
     if((sum[root->mr]-sum[root->ml-])<(sum[root->right->pre]-sum[root->left->suf-]))
     {
         root->mr=root->right->pre;
         root->ml=root->left->suf;
     }
     else if((sum[root->mr]-sum[root->ml-])==(sum[root->right->pre]-sum[root->left->suf-]))
     {
         if(root->left->suf<root->ml||(root->left->suf==root->ml&&root->right->pre<root->mr))
         {
             root->mr=root->right->pre;
             root->ml=root->left->suf;
         }
     }
 }

 void query(tree *root,int ql,int qr,int &x,int &y,int &ansl,int &ansr)
 {
     if((ql<=root->l)&&(root->r<=qr))
     {
         x=root->ml;
         y=root->mr;
         ansl=root->pre;
         ansr=root->suf;
         return;
     }
     int mid=(root->r+root->l)>>;
     if(qr<=mid)query(root->left,ql,qr,x,y,ansl,ansr);
     else if(ql>=mid+)query(root->right,ql,qr,x,y,ansl,ansr);
     else
     {
         int x1,x2,y1,y2,pre1,pre2,suf1,suf2;

         query(root->left,ql,mid,x1,y1,pre1,suf1);
         query(root->right,mid+,qr,x2,y2,pre2,suf2);

         ansl=(sum[pre1]-sum[root->l-])>=(sum[pre2]-sum[root->l-])?pre1:pre2;
         ansr=(sum[root->r]-sum[suf1-])>=(sum[root->r]-sum[suf2-])?suf1:suf2;

         if((sum[y1]-sum[x1-])>=(sum[y2]-sum[x2-]))
         {
             x= x1;
             y= y1;
         }
         else
         {
             x= x2;
             y= y2;
         }
         if((sum[pre2]-sum[suf1-])>(sum[y]-sum[x-]))
         {
             x= suf1;
             y= pre2;
         }
         else if((sum[pre2]-sum[suf1-])==(sum[y]-sum[x-]))
         {
             if((suf1<x)||((suf1==x)&&(pre2<y)))
             {
                 x = suf1;
                 y = pre2;
             }
         }
     }
 }

 int main()
 {
     int n,q,ca=;
     while(scanf("%d%d",&n,&q)!=EOF)
     {
         ll x;
         trcount=;
         memset(sum,,sizeof sum);
         for(int i=; i<=n; i++)
         {
             scanf("%lld",&x);
             sum[i]=sum[i-]+x;
         }
         build(tr,,n);
         int a,b,ans1,ans2,xx,yy;
         printf("Case %d:\n",ca++);
         while(q--)
         {
             scanf("%d%d",&a,&b);
             query(tr,a,b,xx,yy,ans1,ans2);
             printf("%d %d\n",xx,yy);
         }
     }
     return ;
 }