cf 168 k-Multiple Free Set bin_search

来源：互联网发布：python 打包安装程序编辑：程序博客网时间：2024/06/07 00:29

一开始写的是逆序的，WA了，改成正序AC，想来没有道理，细看后才发现是改了当前值，让二分序列不再有序……o(╯□╰)o，正序只能是侥幸罢了

/*author:jxylang:C/C++university:China,Xidian University**If you need to reprint,please indicate the source***/#include <iostream>#include <cstdio>#include <cstdlib>#include <cstring>#include <algorithm>#define INF 1E9using namespace std;int q[100010];int abs(int a){return a>0?a:-a;}int bin(int l,int r,long long x){    int mid;    if(x>abs(q[r]))return -1;    while(l<r)    {        mid=l+((r-l)>>1);        if(abs(q[mid])<x)l=mid+1;        else r=mid;    }    if(q[l]==x)return l;    else return -1;}int main(){    int n,k;    scanf("%d%d",&n,&k);    int i;    for(i=0;i<n;i++)        scanf("%d",&q[i]);    sort(q,q+n);    int ans=0;    for(i=n-1;i>=0;i--)    {        if(q[i]<0)continue;        ans++;        if(q[i]%k==0)        {            r=bin(0,i-1,q[i]/k);            if(r!=-1) q[r]=-q[r];//一开始这是-1        }    }    printf("%d\n",ans);}