leetcode python 常见分类问题模板(复制粘贴就能用) 更新中...

排序 插入、希尔、冒泡、选择

def insertSort(arr):
    for i in range(1,len(arr)):
        tmp = arr[i]
        for j in range(i-1,-1,-1):
            if arr[j] <= tmp:
                arr[j+1] = tmp
                break
            else:
                arr[j+1] = arr[j]
    return arr
def shellSort(arr):
    d = len(arr)//2
    while d>=1:
        for i in range(d,len(arr)):
            tmp = arr[i]
            for j in range(i-d,-1,-1):
                if arr[j] <= tmp:
                    arr[j+d] = tmp
                    break
                else:
                    arr[j+d] = arr[j]
        d=d//2
    return arr
def bubbleSort(arr):
    for i in range(len(arr)):
        for j in range(i+1,len(arr)):
            if arr[i] > arr[j]:
                arr[i],arr[j] =  arr[j],arr[i]
    return arr
def selectSort(arr):
    for i in range(len(arr)-2):
        min_ = arr[i]
        min_i = i
        for j in range(i+1,len(arr)):
            if arr[j] < min_:
                min_ = arr[j]
                min_i = j

        arr[i],arr[min_i] = arr[min_i],arr[i]
    return arr

排序 快速排序及应用

def QuickSort(arr,start,end,k=6):
    if start >= end:
        return
    i,j = start,end
    base = arr[i]
    while i < j:
        while i < j and arr[j] >= base:
            j -=1
        arr[i] = arr[j]
        while i < j and arr[i] <= base:
            i +=1
        arr[j] = arr[i]
    arr[i] = base
    QuickSort(arr, start, i - 1)
    QuickSort(arr, j + 1, end)
#应用 找乱序数组中第K大的数字(也可用最大堆) o(nlogm):
def FindKth(arr,start,end,k=6):
    if start >= end:
        return
    i,j = start,end
    base = arr[i]
    while i < j:
        while i < j and arr[j] >= base:
            j -=1
        arr[i] = arr[j]
        while i < j and arr[i] <= base:
            i +=1
        arr[j] = arr[i]
    arr[i] = base
    #此时 i==j
    if j == k:
        return
    elif k<j: #要找的第K大数在左半边
        FindKth(arr, start, i - 1)
    elif k>j:
        FindKth(arr, j + 1, end)
    return arr[k]

归并排序

#归并排序模板
def merge(nums,left,right):
    mid = (left+right)//2
    if left<right:
        merge(nums,left,mid)
        merge(nums,mid+1,right)
        mergeSort(nums,left,mid,right)
def mergeSort(nums,left,mid,right):#[left,mid][mid+1,right]
    i=left;j=mid+1
    temp = []
    while i<=mid and j<= right:
        if nums[i]<nums[j]:
            temp.append(nums[i])
            i+=1
        else:
            temp.append(nums[j])
            j+=1
    if i<= mid:
        temp.extend(nums[i:mid+1])
    if j<=right:
        temp.extend(nums[j:right+1])
    for i in range(len(temp)):
        nums[left+i] = temp[i]

并查集模板


#init
n = 6
parent = [-1]*n
rank = [0]*n
edges = [(0,1),(1,2),(2,3),(1,4),(2,5)]

def find(x,parent):
    while parent[x] != -1:
        x = parent[x]
    return x 
def union(x,y,parent,rank):
    x_root = find(x,parent)
    y_root = find(y,parent)
    if x_root == y_root:
        return 0
    else:
        if rank[x_root] > rank[y_root]:
            parent[y_root] = x_root
        elif rank[x_root] < rank[y_root]:
            parent[x_root] = y_root
        else:
            parent[x_root] = y_root
            rank[y_root] += 1

        return 1
for i in range(n-1):
    if union(edges[i][0],edges[i][1],parent,rank) == 0:
        print('有环')
    else:
        print('五环')

二分查找模板(check需要自己完成 返回true or false)


def bsearch(nums):
    l = 0;r=len(nums)-1
    while l<r:
        mid = (l+r)>>1#[l,mid][mid+1,r]
        if check(mid):
            r = mid
        else:
            l = mid + 1
def bserach(nums):
    l = 0;r=len(nums)-1
    while l<r:
        mid = (l+r+1)>>1#[l,mid-1][mid,r]
        if check(mid):
            r = mid-1
        else:
            l = mid

堆排序模板


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])

桶排序


def RadixSort(a):
    i = 0                                             #初始为个位排序
    n = 1                                           #最小的位数置为1(包含0)
    max_num = max(a)                       #得到带排序数组中最大数
    while max_num > 10**n:              #得到最大数是几位数
        n += 1
    while i < n:
        bucket = {}                             #用字典构建桶
        for x in range(10):
            bucket.setdefault(x, [])    #将每个桶置空
        for x in a:                               #对每一位进行排序
            radix =int((x / (10**i)) % 10)   #得到每位的基数
            bucket[radix].append(x) #将对应的数组元素加入到相应位基数的桶中
        j = 0
        for k in range(10):
            if len(bucket[k]) != 0:       #若桶不为空
                for y in bucket[k]:         #将该桶中每个元素
                    a[j] = y                       #放回到数组中
                    j += 1
        i += 1


arr = [12,3,45,3543,214,1,4553]
RadixSort(arr)
print(arr)
    原文作者:muddyway
    原文地址: https://segmentfault.com/a/1190000020455950
    本文转自网络文章,转载此文章仅为分享知识,如有侵权,请联系博主进行删除。
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