归并排序模版

#include <iostream>
using namespace std;
int n;
const int N = 1e6+10;
int q[N],tmp[N];
void merge_sort(int l,int r,int q[]){if(l>=r) return;int mid =l+r>>1;merge_sort(l,mid,q);merge_sort(mid+1,r,q);//归并的的过程int k=0,i=l,j=mid+1;while(i<=mid&&j<=r){if(q[i]<=q[j]) tmp[k++]=q[i++];else tmp[k++]=q[j++];}while(i<=mid) tmp[k++]=q[i++];while(j<=r) tmp[k++]=q[j++];for(i=l,j=0;i<=r;i++,j++) q[i]=tmp[j];
}
int main()
{scanf("%d", &n);for (int i = 0; i <n; i ++ ){scanf("%d",&q[i]);}merge_sort(0,n-1,q);for(int i=0;i<n;i++){printf("%d ",q[i]);}
}

快排和二分

 

#include <iostream>
using namespace std;
const int N = 100010;
int n,m;
void quick_sort(int l,int r,int p[]){if(l>=r) return;int i=l-1,j=r+1;int x=p[i+j>>1];while(i<j){do i++;while(p[i]<x);do j--;while(p[j]>x);if(i<j) swap(p[i],p[j]);}quick_sort(l,j,p);quick_sort(j+1,r,p);
}
int main()
{scanf("%d", &n);int p[n];for (int i = 0; i < n; i ++ ){scanf("%d", &p[i]);}quick_sort(0,n-1,p);scanf("%d",&m);int x;for(int i=0;i<m;i++){scanf("%d", &x);int l=0,r=n-1;while(l<r){int mid=l+r >>1;if(p[mid]>=x) r=mid;else l=mid+1;}if(p[l]!=x) printf("NO\n");// else{//     int l=0,r=n-1;//     while(l<r){//         int mid=l+r+1 >> 1;//         if(p[mid]<=x) l=mid;//         else r=mid-1;//     }// }else{printf("YES\n");}}}