青岛实习代码（2）
二分查找递归算法
1 #include <iostream> 2 #include <cstring> 3 #include <algorithm> 4 using namespace std; 5 #define MAXL 10000 6 7 int a[MAXL],key; 8 int BinarySearch(int low,int high) 9 { 10 if(low>high) 11 return -1; 12 13 int mid=(low+high)/2; 14 if(key==a[mid]) 15 return mid; 16 else if(key>a[mid]) 17 return BinarySearch(mid+1,high); 18 else 19 return BinarySearch(low,mid-1); 20 } 21 int main() 22 { 23 int i,N; 24 int f; 25 cin>>N; 26 for(i=0; i<N; i++) 27 cin>>a[i]; 28 cin>>key; 29 f=BinarySearch(0,N-1); 30 if(f==-1) 31 cout<<"no search!"<<endl; 32 else 33 cout<<f<<endl; 34 return 0; 35 }
二分查找非递归算法
1 #include <iostream> 2 #include <cstring> 3 #include <algorithm> 4 using namespace std; 5 #define MAXL 10000 6 7 int BinarySearch(int a[],int n,int key) 8 { 9 int low=0,high=n-1; 10 int mid; 11 while(low<=high) 12 { 13 mid=(low+high)/2; 14 if(key==a[mid]) 15 return mid; 16 else if(key>a[mid]) 17 low=mid+1; 18 else 19 high=mid-1; 20 } 21 return -1; 22 } 23 int main() 24 { 25 int a[MAXL],i,key,N; 26 int f; 27 cin>>N; 28 for(i=0; i<N; i++) 29 cin>>a[i]; 30 cin>>key; 31 f=BinarySearch(a,N,key); 32 if(f==-1) 33 cout<<"no search!"<<endl; 34 else 35 cout<<f<<endl; 36 return 0; 37 }
手写快速排序
1 #include <iostream> 2 #include <cstring> 3 #include <algorithm> 4 using namespace std; 5 #define MAXL 10000 6 7 int a[MAXL],n; 8 void QuickSort(int low,int high) 9 { 10 if(low<high) 11 { 12 int x,l,h; 13 l=low,h=high; 14 x=a[low]; 15 while(low<high) 16 { 17 while(low<high&&a[high]>=x) --high; 18 a[low]=a[high]; 19 while(low<high&&a[low]<=x) ++low; 20 a[high]=a[low]; 21 } 22 a[low]=x; 23 QuickSort(l,low-1); 24 QuickSort(low+1,h); 25 } 26 } 27 28 void show() 29 { 30 int i; 31 for(i=0; i<n; i++) 32 cout<<a[i]<<" "; 33 cout<<endl; 34 } 35 int main() 36 { 37 int i; 38 cin>>n; 39 for(i=0; i<n; i++) 40 cin>>a[i]; 41 QuickSort(0,n-1); 42 show(); 43 return 0; 44 }
