归并排序；
1 //merge sort 2 public static void merge(int[] a,int aux[],int lo ,int mid,int hi ){ 3 int i = lo; 4 int j = mid+1; 5 //copy a 6 for (int k = lo; k <= hi; k++) 7 aux[k] = a[k]; 8 //merge 9 for(int k = lo;k<=hi;k++){ 10 //先判断是否越界 11 if(i>mid) a[k]=aux[j++]; 12 else if(j>hi) a[k]=aux[i++]; 13 // merge 14 else if(aux[j]<=aux[i]) a[k]=aux[j++]; 15 else a[k]=aux[i++]; 16 } 17 } 18 public static void mergesort(int[] a,int aux[],int lo,int hi) { 19 //边界条件 20 if(lo>=hi) return ; 21 int mid = (hi-lo)/2+lo; 22 mergesort(a,aux, lo, mid); 23 mergesort(a,aux, mid+1, hi); 24 merge(a,aux, lo, mid, hi); 25 26 } 27 public static void mergeSort(int[] a){ 28 int aux[] = new int[a.length]; 29 mergesort(a,aux, 0, a.length-1); 30 }
1 ef merge(a,aux,lo,mid,hi): 2 if(lo>=hi) : 3 return a 4 5 ####merge之前copy 6 aux = a.copy() 7 8 i = lo 9 j = mid + 1 10 k = lo 11 while i<=mid and j<=hi: 12 if(aux[i]<aux[j]): 13 a[k] = aux[i];i+=1;k+=1 14 else: 15 a[k] = aux[j];j+=1;k+=1 16 while i<=mid: 17 a[k] = aux[i] ;i+=1;k+=1 18 while j<=hi: 19 a[k] = aux[j] ;j+=1;k+=1 20 return a 21 def merge_sort(a,aux,lo,hi): 22 if(lo>=hi): 23 return 24 mid = int((hi-lo)/2) +lo 25 print(a,aux,lo,mid,hi) 26 merge_sort(a,aux,lo,mid) 27 merge_sort(a,aux,mid+1,hi) 28 merge(a,aux,lo,mid,hi) 29 return a 30 def merge_sort1(a): 31 merge_sort(a,a.copy(),0,len(a)-1)
快速排序：
1 //quick sort 2 //partion 3 private static int partion(int[] a ,int lo,int hi) { 4 int v = a[lo]; 5 int i = lo ,j=hi+1; 6 while(true){ 7 while(a[++i]<v) if(i>=hi) break; 8 while(a[--j]>v) if(j<=lo) break; 9 if(i>=j) break; 10 swap(a, i, j); 11 } 12 swap(a, lo, j); 13 return j; 14 } 15 public static void partionsort(int[] a,int lo,int hi) { 16 if(lo>=hi) return; 17 int j = partion(a, lo, hi); 18 partionsort(a, lo, j); 19 partionsort(a, j+1, hi); 20 21 } 22 public static void partionSort(int[] a) { 23 partionsort(a, 0, a.length-1); 24 } 25
1 def quick_sort1(x): 2 def partion(a, lo, hi): 3 ''' 4 得到数组a的划分 5 以a[lo] 为key,最后把a[lo]放在最终排序的位置 6 且 a[lo] 前面的比其都小，a[lo]后面的比其都大 7 ''' 8 key = a[lo] 9 i = lo 10 j = hi 11 while(i < j): 12 # 必须带等号 13 while(i < hi and a[i] <= key): # 从左往右找到大于key的下标 14 i += 1 15 while(j > lo and a[j] >= key): # 从右往左找到小于key的下标 16 j -= 1 17 if i < j: # 如果下标i小于下标j则交换，没有越界 18 swap(a, i, j) 19 swap(a, lo, j) 20 return j 21 22 def quick_sort(x, lo, hi): 23 if lo >= hi: 24 return 25 i = partion(x, lo, hi) 26 print(x) 27 quick_sort(x, lo, i) 28 quick_sort(x, i + 1, hi) 29 print(x) 30 31 quick_sort(x, 0, len(x) - 1) 32 return x