CF-1108E2线段树

Posted 2021-03-11 tombraider-shadow

E2. Array and Segments (Hard version)

题目链接：https://codeforces.com/problemset/problem/1108/E2

解题思路：线段树

blog：https://blog.csdn.net/Floraqiu/article/details/86632558

 

代码

 

#include<bits/stdc++.h>
using namespace std;
const int maxn=1e5+5;
const int maxm=300;
int n,m;
int a[maxn],l[maxm],r[maxm],ans[maxn];
vector<int>add[maxn],sub[maxn];
struct node
{
    int l,r,lazy;
    int maxx;int minn;
 } tree[maxn<<2];
void push_up(int k)
{
     tree[k].maxx=max(tree[k<<1].maxx,tree[k<<1|1].maxx);
     tree[k].minn=min(tree[k<<1].minn,tree[k<<1|1].minn);
}
void push_down(int k)
{
    if(tree[k].l != tree[k].r)
    {
        tree[k << 1].maxx += tree[k].lazy, tree[k << 1].minn += tree[k].lazy;
        tree[k << 1 | 1].maxx += tree[k].lazy, tree[k << 1 | 1].minn += tree[k].lazy;
        tree[k << 1].lazy += tree[k].lazy;
        tree[k << 1 | 1].lazy += tree[k].lazy;
    }
    tree[k].lazy = 0;
}
void build(int k,int l,int r)
{
    tree[k].l=l,tree[k].r=r;
    if(l==r)
    {
        tree[k].maxx=a[l];
        tree[k].minn=a[r];
        tree[k].lazy=0;
        return ;
    }
    int mid=(l+r)>>1;
    build(k<<1,l,mid);
    build(k<<1|1,mid+1,r);
    push_up(k);
}
void update(int k, int l, int r, int x)
{
    if(tree[k].lazy)
        push_down(k);
    tree[k].maxx += x;
    tree[k].minn += x;
    if(tree[k].l == l && tree[k].r == r)
    {
        tree[k].lazy += x;
        return ;
    }
    int mid = (tree[k].l + tree[k].r) >> 1;
    if(r <= mid)
        update(k << 1, l, r, x);
    else if(l > mid)
        update(k << 1 | 1, l, r, x);
    else
    {
        update(k << 1, l, mid, x);
        update(k << 1 | 1, mid + 1, r, x);
    }
    push_up(k);
}

int query_max(int k, int l, int r)
{
    int maxx;
    if(tree[k].lazy)
        push_down(k);
    if(tree[k].l == l && tree[k].r == r)
        return tree[k].maxx;
    int mid = (tree[k].l + tree[k].r) >> 1;
    if(r <= mid)
        maxx = query_max(k << 1, l, r);
    else if(l > mid)
        maxx = query_max(k << 1 | 1, l, r);
    else
        maxx = max(query_max(k << 1, l, mid), query_max(k << 1 | 1, mid + 1, r));
    return maxx;
}

int query_min(int k, int l, int r)
{
    int minn;
    if(tree[k].lazy)
        push_down(k);
    if(tree[k].l == l && tree[k].r == r)
        return tree[k].minn;
    int mid = (tree[k].l + tree[k].r) >> 1;
    if(r <= mid)
        minn = query_min(k << 1, l, r);
    else if(l > mid)
        minn = query_min(k << 1 | 1, l, r);
    else
        minn = min(query_min(k << 1, l, mid), query_min(k << 1 | 1, mid + 1, r));
    return minn;
}
int main()
{
    cin>>n>>m;
    for(int i=1;i<=n;i++)
    {
        cin>>a[i];
    }
    for(int i=1;i<=m;i++)
    {
        cin>>l[i]>>r[i];
        sub[l[i]].push_back(i);
        add[r[i]].push_back(i);
    }
    build(1,1,n);
    int d=-0x3f3f3f,p;
    for(int i=1;i<=n;i++)
    {
        for(int j=0;j<add[i-1].size();j++)
        {
            int id=add[i-1][j];
            update(1,l[id],r[id],1);
         }
        for(int j=0;j<sub[i].size();j++)
        {
            int id=sub[i][j];
            update(1,l[id],r[id],-1);
        }
        int det = query_max(1, 1, n) - query_min(1, 1, n);
         if(det>d)
         {
             d=det;
             p=i;
         }
    }
    cout<<d<<endl;
    int cnt=0;
    for(int i=1; i<=m; i++)//统计区间
    {
        if(l[i]<=p&&p<=r[i])
            ans[cnt++] = i;
    }
    cout<<cnt<<endl;
    for(int i=0;i<cnt;i++)
    {
        if(i!=0)
            cout<<" ";
        cout<<ans[i];
    }
    cout<<endl;
    return 0;
 }