//居然1Y了，，，我。。。
#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;
int m,n;
int a[60000];
enum COLOR
{
    red,black
};
struct RedBlack
{
    COLOR color;
    int l;
    int r;
    int p;
    int key;
    int cnt;
};
RedBlack tree[60000];
int lt;
int root;
void RB_Init()
{
    tree[0].color=black;
    tree[0].key=-1;
    root=1;
    tree[1].l=0;
    tree[1].r=0;
    tree[1].p=0;
    tree[1].cnt=0;
    tree[1].key=-1;
}
void RB_KeyC_Fixup(int x)
{
    tree[x].cnt=tree[tree[x].l].cnt+tree[tree[x].r].cnt+1;
}
void RB_Left_Rotate(int x)
{
    int y;
    y=tree[x].r;
    tree[x].r=tree[y].l;
    if (tree[y].l != 0)
    {
        tree[tree[y].l].p=x;
    }
    tree[y].p=tree[x].p;
    if (tree[x].p == 0)
    {
        root=y;
    }
    else if (tree[x].p != 0 && x == tree[tree[x].p].l)
    {
        tree[tree[x].p].l=y;
    }
    else if (tree[x].p != 0 && x != tree[tree[x].p].l)
    {
        tree[tree[x].p].r=y;
    }
    tree[y].l=x;
    tree[x].p=y;
    RB_KeyC_Fixup(x);
    RB_KeyC_Fixup(y);
}
void RB_Right_Rotate(int y)
{
    int x;
    x=tree[y].l;
    tree[y].l=tree[x].r;
    if (tree[x].r != 0)
    {
        tree[tree[x].r].p=y;
    }
    tree[x].p=tree[y].p;
    if (tree[y].p == 0)
    {
        root=x;
    }
    else if (tree[y].p != 0 && y == tree[tree[y].p].l)
    {
        tree[tree[y].p].l=x;
    }
    else if (tree[y].p != 0 && y != tree[tree[y].p].l)
    {
        tree[tree[y].p].r=x;
    }
    tree[x].r=y;
    tree[y].p=x;
    RB_KeyC_Fixup(y);
    RB_KeyC_Fixup(x);
}
void RB_Insert_Fixup(int z)
{
    int y;
    while (tree[tree[z].p].color == red)
    {
        if (tree[z].p == tree[tree[tree[z].p].p].l)
        {
            y=tree[tree[tree[z].p].p].r;
            if (tree[y].color == red)
            {
                tree[tree[z].p].color=black;
                tree[y].color=black;
                tree[tree[tree[z].p].p].color=red;
                z=tree[tree[z].p].p;
            }
            else if (tree[y].color != red && z == tree[tree[z].p].r)
            {
                z=tree[z].p;
                RB_Left_Rotate(z);
            }
            else if (tree[y].color != red && z == tree[tree[z].p].l)
            {
                tree[tree[z].p].color=black;
                tree[tree[tree[z].p].p].color=red;
                RB_Right_Rotate(tree[tree[z].p].p);
            }
        }
        else
        {
            y=tree[tree[tree[z].p].p].l;
            if (tree[y].color == red)
            {
                tree[tree[z].p].color=black;
                tree[y].color=black;
                tree[tree[tree[z].p].p].color=red;
                z=tree[tree[z].p].p;
            }
            else if (tree[y].color != red && z == tree[tree[z].p].l)
            {
                z=tree[z].p;
                RB_Right_Rotate(z);
            }
            else if (tree[y].color != red && z == tree[tree[z].p].r)
            {
                tree[tree[z].p].color=black;
                tree[tree[tree[z].p].p].color=red;
                RB_Left_Rotate(tree[tree[z].p].p);
            }
        }
    }
    tree[root].color=black;
}
void RB_Insert(int n)
{
    int x,y;
    y=0;
    x=root;
    while (tree[x].key != -1)
    {
        y=x;
        tree[x].cnt++;
        if (n < tree[x].key)
        {
            x=tree[x].l;
        }
        else
        {
            x=tree[x].r;
        }
    }
    tree[lt].p=y;
    if (y == 0)
    {
        root=lt;
    }
    else if (y != 0 && n < tree[y].key)
    {
        tree[y].l=lt;
    }
    else if (y != 0 && n >= tree[y].key)
    {
        tree[y].r=lt;
    }
    tree[lt].l=0;
    tree[lt].r=0;
    tree[lt].color=red;
    tree[lt].key=n;
    tree[lt].cnt=1;
    RB_Insert_Fixup(lt);
    lt++;
}
int RB_Query(int k)
{
    int x,y;
    x=root;
    while (k != 1 || tree[x].cnt != 1)
    {
       // printf("->%d %d\n",k,tree[x].key);
        if (k <= tree[tree[x].l].cnt && tree[x].l != 0)
        {
            x=tree[x].l;
        }
        else if (k == tree[tree[x].l].cnt+1)
        {
            return tree[x].key;
        }
        else if (k > tree[tree[x].l].cnt+1)
        {
            k-=tree[tree[x].l].cnt+1;
            x=tree[x].r;
        }
        //printf("->%d %d %d\n",k,tree[x].key,tree[x].cnt);
    }
    return tree[x].key;
}
void printTree(int x)
{
    if (tree[x].l != 0)
        printTree(tree[x].l);
    printf("[%d %d]\n",tree[x].key,tree[x].cnt);
    if (tree[x].r!= 0)
        printTree(tree[x].r);
}
int main()
{
    int i,j,pr,t,p;
    scanf("%d%d",&m,&n);
    for (i=1; i<=m; i++)
    {
        scanf("%d",a+i);
    }
    pr=1;
    p=1;
    lt=1;
    RB_Init();
    while (n--)
    {
        scanf("%d",&t);
        for (i=pr; i<=t; i++)
        {
          //  printf("i=%d\n",i);
            RB_Insert(a[i]);
        }
       // printTree(root);
        pr=t+1;
        printf("%d\n",RB_Query(p));
        p++;
    }
}

• Re:第一次写红黑树，居然1Y了。。你敢信？？ (3708) hz666 2023-07-18 17:38:22