快速排序-合并排序（分治法运用）

快速排序

#include 
using namespace std;

#define N 10
int a[N]={3,3,56,7,4,4,3,2,2,3};

void swap(int i,int j);
int partition(int begin,int end);
void quicksort(int begin,int end);
int main(){
	quicksort(0,N-1);
	int i;
	for(i = 0; i < N; i++){
	 cout << a[i] << " ";
	}
	cout << endl;
	return 0;
}

void quicksort(int begin,int end){
	int j;
	if(begin < end){
		j=partition(begin,end);
		quicksort(begin,j-1);
		quicksort(j+1,end);
	}
}

int partition(int begin,int end){
	int i = begin,j = end+1;
	do{
		do{
			i++;
		}while(a[i] < a[begin]);
		
		do{
			j--;
		}while(a[j] > a[begin]);
		if(i<=j){
			swap(i,j);
		}
	}while(i<=j);
	swap(begin,j);
	return j;
}

void swap(int i,int j){
	int tmp;
	tmp = a[i];
	a[i] = a[j];
	a[j] = tmp;
}

合并排序

/*归并排序*/
#include 
using namespace std;

#define N 10
int a[N]={1,2,3,93,5,6,39,8,4,9};


void merge_sort(int begin,int end,int a[]);
void merge(int begin,int mid,int end);
int main(){
	    merge_sort(0,N-1,a);
		int i;
		for(i = 0; i < N; i++){
			cout << a[i] << " ";
		}
		cout << endl;
	return 0;
}

void merge_sort(int begin,int end,int a[]){
	int m;
	if(begin < end){
		m = (begin + end)/2;
		merge_sort(begin,m,a);
		merge_sort(m+1,end,a);
		merge(begin,m,end);
	}
}

void merge(int begin,int mid,int end){
	int T[N];
	int i = begin, j = mid+1,k = begin;
	while(i <= mid || j <= end){
		if((j > end)||(i <= mid && a[i] <= a[j])){
			T[k++] = a[i++]; 	
		}
		else{
			T[k++] = a[j++]; 
		}
	}
	for(i=begin,k=begin;k<=end;){
		a[k++] = T[i++];
	}
}