COGS 1534 [NEERC 2004]K小数 &&COGS 930 [河南省队2012] 找第k小的数 可持久化01Trie

Posted 2020-10-01 TS_Hugh

板子题，只是记得负数加fix最方便

#include <cstdio>
const int A=19,N=100010;
namespace FIFO 
{
    char ch,B[1<<20],*S=B,*T=B;
    #define getc() (S==T&&(T=(S=B)+fread(B,1,1<<20,stdin),S==T)?0:*S++)
    #define isd(c) (c>=‘0‘&&c<=‘9‘)
    int aa,bb;int F(){
        while(ch=getc(),!isd(ch)&&ch!=‘-‘);ch==‘-‘?aa=bb=0:(aa=ch-‘0‘,bb=1);
        while(ch=getc(),isd(ch))aa=aa*10+ch-‘0‘;return bb?aa:-aa;
    }
}
#define gi FIFO::F()
struct Trie{
    Trie *ch[2];int size;
}*root[N],*null,node[(1<<22)+10];
int n,m,sz=1;
int main(){
    freopen("kth.in","r",stdin);freopen("kth.out","w",stdout);
    null=node,null->ch[0]=null->ch[1]=null,root[0]=null;
    n=gi,m=gi;for(register int i=1,x;i<=n;i++){
        root[i]=node+sz,sz++,x=gi;register Trie *p=root[i],*last=root[i-1];
        for(register int i=A;i>=0;i--)
            p->ch[(x>>i)&1]=node+sz,sz++,p->ch[((x>>i)&1)^1]=last->ch[((x>>i)&1)^1],
            p=p->ch[(x>>i)&1],last=last->ch[(x>>i)&1],p->size=last->size+1;
    }
    register int x,y,k;while(m--){
        x=gi,y=gi,k=gi;register Trie *a=root[x-1],*b=root[y];register int ret=0;
        for(register int i=A;i>=0;i--)
            if(b->ch[0]->size-a->ch[0]->size>=k)a=a->ch[0],b=b->ch[0];
            else ret|=(1<<i),k-=b->ch[0]->size-a->ch[0]->size,a=a->ch[1],b=b->ch[1];
        printf("%d\n",ret);
    }
}

【COGS 930】 [河南省队2012] 找第k小的数

#include <cstdio>
const int A=30,N=100010,fox=1000000000;
namespace FIFO 
{
    char ch,B[1<<20],*S=B,*T=B;
    #define getc() (S==T&&(T=(S=B)+fread(B,1,1<<20,stdin),S==T)?0:*S++)
    #define isd(c) (c>=‘0‘&&c<=‘9‘)
    int aa,bb;int F(){
        while(ch=getc(),!isd(ch)&&ch!=‘-‘);ch==‘-‘?aa=bb=0:(aa=ch-‘0‘,bb=1);
        while(ch=getc(),isd(ch))aa=aa*10+ch-‘0‘;return bb?aa:-aa;
    }
}
#define gi FIFO::F()
struct Trie{
    Trie *ch[2];int size;
}*root[N],*null,node[(1<<22)+10];
int n,m,sz=1;
int main(){
    freopen("kthnumber.in","r",stdin);freopen("kthnumber.out","w",stdout);
    null=node,null->ch[0]=null->ch[1]=null,root[0]=null;
    n=gi,m=gi;for(register int i=1,x;i<=n;i++){
        root[i]=node+sz,sz++,x=gi+fox;register Trie *p=root[i],*last=root[i-1];
        for(register int i=A;i>=0;i--)
            p->ch[(x>>i)&1]=node+sz,sz++,p->ch[((x>>i)&1)^1]=last->ch[((x>>i)&1)^1],
            p=p->ch[(x>>i)&1],last=last->ch[(x>>i)&1],p->size=last->size+1;
    }
    register int x,y,k;while(m--){
        x=gi,y=gi,k=gi;register Trie *a=root[x-1],*b=root[y];register int ret=0;
        for(register int i=A;i>=0;i--)
            if(b->ch[0]->size-a->ch[0]->size>=k)a=a->ch[0],b=b->ch[0];
            else ret|=(1<<i),k-=b->ch[0]->size-a->ch[0]->size,a=a->ch[1],b=b->ch[1];
        printf("%d\n",ret-fox);
    }
}

【COGS 1534】 [NEERC 2004]K小数