uva 1400

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*2];

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)/2;
    build(root->left,l,mid);
    build(root->right,mid+1,r);

    //update the pre
    if((sum[root->left->pre]-sum[root->l-1])>=(sum[root->right->pre]-sum[root->l-1]))
        root->pre=root->left->pre;
    else root->pre=root->right->pre;
    //update the suf
    if((sum[root->r]-sum[root->left->suf-1])>=(sum[root->r]-sum[root->right->suf-1]))
        root->suf=root->left->suf;
    else root->suf=root->right->suf;
    //update the max
    if((sum[root->left->mr]-sum[root->left->ml-1])>=(sum[root->right->mr]-sum[root->right->ml-1]))
    {
        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-1])<(sum[root->right->pre]-sum[root->left->suf-1]))
    {
        root->mr=root->right->pre;
        root->ml=root->left->suf;
    }
    else if((sum[root->mr]-sum[root->ml-1])==(sum[root->right->pre]-sum[root->left->suf-1]))
    {
        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)>>1;
    if(qr<=mid)query(root->left,ql,qr,x,y,ansl,ansr);
    else if(ql>=mid+1)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+1,qr,x2,y2,pre2,suf2);

        ansl=(sum[pre1]-sum[root->l-1])>=(sum[pre2]-sum[root->l-1])?pre1:pre2;
        ansr=(sum[root->r]-sum[suf1-1])>=(sum[root->r]-sum[suf2-1])?suf1:suf2;

        if((sum[y1]-sum[x1-1])>=(sum[y2]-sum[x2-1]))
        {
            x= x1;
            y= y1;
        }
        else
        {
            x= x2;
            y= y2;
        }
        if((sum[pre2]-sum[suf1-1])>(sum[y]-sum[x-1]))
        {
            x= suf1;
            y= pre2;
        }
        else if((sum[pre2]-sum[suf1-1])==(sum[y]-sum[x-1]))
        {
            if((suf1<x)||((suf1==x)&&(pre2<y)))
            {
                x = suf1;
                y = pre2;
            }
        }
    }
}


int main()
{
    int n,q,ca=1;
    while(scanf("%d%d",&n,&q)!=EOF)
    {
        ll x;
        trcount=0;
        memset(sum,0,sizeof sum);
        for(int i=1; i<=n; i++)
        {
            scanf("%lld",&x);
            sum[i]=sum[i-1]+x;
        }
        build(tr,1,n);
        int a,b,ans1,ans2,xx,yy;
        printf("Case %d:
",ca++);
        while(q--)
        {
            scanf("%d%d",&a,&b);
            query(tr,a,b,xx,yy,ans1,ans2);
            printf("%d %d
",xx,yy);
        }
    }
    return 0;
}