AC日记——Rmq Problem bzoj 3339

Posted 2020-09-20 Only U - IU

3339

 

思路；

　　恶心；

 

代码：

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>

using namespace std;

#define maxn 200005

struct TreeNodeType {
    int l,r,dis,mid,flag;
    
    bool if_;
};
struct TreeNodeType tree[maxn<<2];

struct QueryType {
    int l,r,id;
};
struct QueryType qu[maxn];

int n,m,ai[maxn],sg[maxn],ans[maxn],Next[maxn],last[maxn];
int num[maxn];

inline void in(int &now)
{
    char Cget=getchar();now=0;
    while(Cget>‘9‘||Cget<‘0‘) Cget=getchar();
    while(Cget>=‘0‘&&Cget<=‘9‘)
    {
        now=now*10+Cget-‘0‘;
        Cget=getchar();
    }
}

void tree_build(int now,int l,int r)
{
    tree[now].l=l,tree[now].r=r;
    if(l==r) { tree[now].dis=sg[l];return; }
    tree[now].mid=l+r>>1;
    tree_build(now<<1,l,tree[now].mid);
    tree_build(now<<1|1,tree[now].mid+1,r);
    tree[now].dis=min(tree[now<<1].dis,tree[now<<1|1].dis);
}

void tree_down(int now)
{
    tree[now<<1].dis=min(tree[now<<1].dis,tree[now].flag);
    tree[now<<1|1].dis=min(tree[now<<1|1].dis,tree[now].flag);
    if(tree[now<<1].if_) tree[now<<1].flag=min(tree[now<<1].flag,tree[now].flag);
    else tree[now<<1].flag=tree[now].flag,tree[now<<1].if_=true;
    if(tree[now<<1|1].if_) tree[now<<1|1].flag=min(tree[now<<1|1].flag,tree[now].flag);
    else tree[now<<1|1].flag=tree[now].flag,tree[now<<1|1].if_=true;
    tree[now].if_=false;return ;
}

void tree_change(int now,int l,int r,int x)
{
    if(tree[now].l==l&&tree[now].r==r)
    {
        tree[now].dis=min(tree[now].dis,x);
        if(tree[now].if_) tree[now].flag=min(tree[now].flag,x);
        else tree[now].flag=x,tree[now].if_=true;
        return ;
    }
    if(tree[now].if_) tree_down(now);
    if(r<=tree[now].mid) tree_change(now<<1,l,r,x);
    else if(l>tree[now].mid) tree_change(now<<1|1,l,r,x);
    else tree_change(now<<1,l,tree[now].mid,x),tree_change(now<<1|1,tree[now].mid+1,r,x);
    tree[now].dis=min(tree[now<<1].dis,tree[now<<1|1].dis);
}

int tree_query(int now,int to)
{
    if(tree[now].l==tree[now].r) return tree[now].dis;
    if(tree[now].if_) tree_down(now);
    if(to<=tree[now].mid) return tree_query(now<<1,to);
    else return tree_query(now<<1|1,to);
}

bool cmp(QueryType aa,QueryType bb)
{
    return aa.l<bb.l;
}

int main()
{
    freopen("mex.in","r",stdin);
    freopen("mex.out","w",stdout);
    in(n),in(m);int now=0;
    for(int i=1;i<=n;i++) in(ai[i]);
    for(int i=1;i<=n;i++)
    {
        num[ai[i]]++;
        while(num[now]) now++;
        sg[i]=now;
        if(last[ai[i]]) Next[last[ai[i]]]=i;
        last[ai[i]]=i;
    }
    sg[n+1]=now;tree_build(1,1,n);
    for(int i=1;i<=n;i++) if(!Next[i]) Next[i]=n+1;
    for(int i=1;i<=m;i++) in(qu[i].l),in(qu[i].r),qu[i].id=i;
    sort(qu+1,qu+m+1,cmp),now=1;
    for(int no=1;no<=m;no++)
    {
        while(now<qu[no].l) tree_change(1,now,Next[now]-1,ai[now]),now++;
        ans[qu[no].id]=tree_query(1,qu[no].r);
    }
    for(int i=1;i<=m;i++) printf("%d\n",ans[i]);
    return 0;
}