算法导论：第二章总结

SELECTION-SORT(A)

n : length[A]
	for j : 1 to n − 1
		do smallest : j
			for i : j + 1 to n
				do if A[i] < A[smallest] 
					then smallest : i
			exchange A[j] and A[smallest]

INSERTION-SORT（A）

for j : 2 to length[A]
	do key : A[j]
	i : j-1
	while i>0 and A[i]>key
		do A[i+1] : A[i]
			i : i-1
	A[i+1] : key

MERGE(A, p, q, r) 
n1 : q-p+1 
n2 : r-q 
create arrays L[1..n1+1] and R[1..n2+1]
for i : 1 to n1     
	do L[i] : A[p+i-1] 
for j : 1 to n2     
	do R[j] : A[q+j]
L[n1+1] :  ∞
L[n2+1] :  ∞
i : 1
j : 1
for k : p to r
	do if L[i]<=R[j]
		then A[k] : L[i]
			i : i+1
		else A[k] : R[j]
			j : j+1

MERGE-SORT(a, p, r)

if p<r
	then q : (p+r)/2
		MERGE-SORT(A, p , q)
		MERGE-SORT(A, q+1, r)
		MERGE(a, p, q, r)

  

BUBBLESORT(A)

for i : 1 to length[A]
    do for j : length[A] downto i+1
        do if A[j] < A[j-1]
            then exchange A[j] and A[j-1]

自己的插入排序：

#include <stdio.h>
#include <string.h>
#define N 12

int A[N] ={0,4,8,5,9,1,6,3};


void insertion_sort(int A[]){
    int key,i,j;
    for(j=2; j<8; ++j){
        key = A[j];
        i = j-1;
        while(i>0 && A[i]>key){
            A[i+1] = A[i];
            i = i-1;
        }
        A[i+1] = key;
    }
}

int main(int argc, char const *argv[])
{
    
    insertion_sort(A);
    for (int i = 0; i < 10; ++i)
    {
        printf("%d ", A[i]);
    }
    printf("
");
    return 0

自己写的合并排序：

#include <stdio.h>  
#include <iostream>  
using namespace std; 
 
void Merge(int* A,int p,int q,int r) 
{ 
    int n1= q-p+1; 
    int n2= r-q; 
     
    int *L= new int[n1+1]; 
    int *R= new int[n2+1]; 
 
    int i=0; 
    int j=0; 
 
    for(i=0;i<n1;i++) 
    { 
        L[i]=A[p+i-1]; 
         
    } 
     
    for(j=0;j<n2;j++) 
    { 
        R[j]=A[q+j]; 
     
    } 
    L[n1] = 100;
    R[n2] = 100;
     
    i = 0; 
    j = 0; 
     
    for(int k = p-1;k < r; k++) 
    { 
        if(L[i]<=R[j]) 
        { 
            A[k] = L[i]; 
            i = i+1;    
        } 
        else 
        { 
            A[k] = R[j]; 
            j = j+1;     
        } 
    } 
}  
 
void Merge_Sort(int *A,int p,int r) 
{ 
    if(p<r) 
    { 
        int q=(p+r)/2; 
        Merge_Sort(A,p,q); 
        Merge_Sort(A,q+1,r); 
        Merge(A,p,q,r); 
    } 
} 
 
int A[15] = {11,12,13,14,15,1,2,3,4,5,6,7,8,9,10};  
 
int main(int argc, char **argv) 
{ 
    Merge_Sort(A,1,15); 
     
    for(int i=0;i<15;i++) 
    { 
        cout<<A[i]<<"	"; 
    } 
    cout<<endl; 
    return 0; 
}