def search(arr, n, x):
for i in range (0, n):
if (arr[i] == x):
return i;
return -1;
# 在数组 arr 中查找字符 D
arr = [ 'A', 'B', 'C', 'D', 'E' ]
x = 'D'
n = len(arr)
result = search(arr, n, x)
if(result == -1):
print("元素不在数组中")
else:
print("元素在数组中的索引为", result)
0x02 插入排序
def insertionSort(arr):
for i in range(1, len(arr)):
key = arr[i]
j = i-1
while j >=0 and key < arr[j] :
arr[j+1] = arr[j]
j -= 1
arr[j+1] = key
arr = [12, 11, 13, 5, 6]
insertionSort(arr)
print ("排序后的数组:")
for i in range(len(arr)):
print ("%d" %arr[i])
0x03 快速排序
def partition(arr,low,high):
i = ( low-1 ) # 最小元素索引
pivot = arr[high]
for j in range(low , high):
# 当前元素小于或等于 pivot
if arr[j] <= pivot:
i = i+1
arr[i],arr[j] = arr[j],arr[i]
arr[i+1],arr[high] = arr[high],arr[i+1]
return ( i+1 )
# arr[] --> 排序数组
# low --> 起始索引
# high --> 结束索引
# 快速排序函数
def quickSort(arr,low,high):
if low < high:
pi = partition(arr,low,high)
quickSort(arr, low, pi-1)
quickSort(arr, pi+1, high)
arr = [10, 7, 8, 9, 1, 5]
n = len(arr)
quickSort(arr,0,n-1)
print ("排序后的数组:")
for i in range(n):
print ("%d" %arr[i])
0x04 选择排序
import sys
A = [64, 25, 12, 22, 11]
for i in range(len(A)):
min_idx = i
for j in range(i+1, len(A)):
if A[min_idx] > A[j]:
min_idx = j
A[i], A[min_idx] = A[min_idx], A[i]
print ("排序后的数组:")
for i in range(len(A)):
print("%d" %A[i])
0x05 冒泡排序
def bubbleSort(arr):
n = len(arr)
# 遍历所有数组元素
for i in range(n):
# Last i elements are already in place
for j in range(0, n-i-1):
if arr[j] > arr[j+1] :
arr[j], arr[j+1] = arr[j+1], arr[j]
arr = [64, 34, 25, 12, 22, 11, 90]
bubbleSort(arr)
print ("排序后的数组:")
for i in range(len(arr)):
print ("%d" %arr[i])
0x06 归并排序
def merge(arr, l, m, r):
n1 = m - l + 1
n2 = r- m
# 创建临时数组
L = [0] * (n1)
R = [0] * (n2)
# 拷贝数据到临时数组 arrays L[] 和 R[]
for i in range(0 , n1):
L[i] = arr[l + i]
for j in range(0 , n2):
R[j] = arr[m + 1 + j]
# 归并临时数组到 arr[l..r]
i = 0 # 初始化第一个子数组的索引
j = 0 # 初始化第二个子数组的索引
k = l # 初始归并子数组的索引
while i < n1 and j < n2 :
if L[i] <= R[j]:
arr[k] = L[i]
i += 1
else:
arr[k] = R[j]
j += 1
k += 1
# 拷贝 L[] 的保留元素
while i < n1:
arr[k] = L[i]
i += 1
k += 1
# 拷贝 R[] 的保留元素
while j < n2:
arr[k] = R[j]
j += 1
k += 1
def mergeSort(arr,l,r):
if l < r:
m = int((l+(r-1))/2)
mergeSort(arr, l, m)
mergeSort(arr, m+1, r)
merge(arr, l, m, r)
arr = [12, 11, 13, 5, 6, 7]
n = len(arr)
print ("给定的数组")
for i in range(n):
print ("%d" %arr[i]),
mergeSort(arr,0,n-1)
print ("\n\n排序后的数组")
for i in range(n):
print ("%d" %arr[i]),
0x07 堆排序
def heapify(arr, n, i):
largest = i
l = 2 * i + 1 # left = 2*i + 1
r = 2 * i + 2 # right = 2*i + 2
if l < n and arr[i] < arr[l]:
largest = l
if r < n and arr[largest] < arr[r]:
largest = r
if largest != i:
arr[i],arr[largest] = arr[largest],arr[i] # 交换
heapify(arr, n, largest)
def heapSort(arr):
n = len(arr)
# Build a maxheap.
for i in range(n, -1, -1):
heapify(arr, n, i)
# 一个个交换元素
for i in range(n-1, 0, -1):
arr[i], arr[0] = arr[0], arr[i] # 交换
heapify(arr, i, 0)
arr = [ 12, 11, 13, 5, 6, 7]
heapSort(arr)
n = len(arr)
print ("排序后")
for i in range(n):
print ("%d" %arr[i]),
0x08 基数排序
def countSort(arr):
output = [0 for i in range(256)]
count = [0 for i in range(256)]
ans = ["" for _ in arr]
for i in arr:
count[ord(i)] += 1
for i in range(256):
count[i] += count[i-1]
for i in range(len(arr)):
output[count[ord(arr[i])]-1] = arr[i]
count[ord(arr[i])] -= 1
for i in range(len(arr)):
ans[i] = output[i]
return ans
arr = "wwwrunoobcom"
ans = countSort(arr)
print ( "字符数组排序 %s" %("".join(ans)) )
0x09 希尔排序
def shellSort(arr):
n = len(arr)
gap = int(n/2)
while gap > 0:
for i in range(gap,n):
temp = arr[i]
j = i
while j >= gap and arr[j-gap] >temp:
arr[j] = arr[j-gap]
j -= gap
arr[j] = temp
gap = int(gap/2)
arr = [ 12, 34, 54, 2, 3]
n = len(arr)
print ("排序前:")
for i in range(n):
print(arr[i]),
shellSort(arr)
print ("\n排序后:")
for i in range(n):
print(arr[i]),
0x0A 拓扑排序
from collections import defaultdict
class Graph:
def __init__(self,vertices):
self.graph = defaultdict(list)
self.V = vertices
def addEdge(self,u,v):
self.graph[u].append(v)
def topologicalSortUtil(self,v,visited,stack):
visited[v] = True
for i in self.graph[v]:
if visited[i] == False:
self.topologicalSortUtil(i,visited,stack)
stack.insert(0,v)
def topologicalSort(self):
visited = [False]*self.V
stack =[]
for i in range(self.V):
if visited[i] == False:
self.topologicalSortUtil(i,visited,stack)
print (stack)
g= Graph(6)
g.addEdge(5, 2);
g.addEdge(5, 0);
g.addEdge(4, 0);
g.addEdge(4, 1);
g.addEdge(2, 3);
g.addEdge(3, 1);
print ("拓扑排序结果:")
g.topologicalSort()