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python 演算法歸類

1.斐波那契數列

def func(n):
    a = 0
    b = 1
    alist = []
    if n <= 2:
        alist.append(a)
        alist.append(b)
        return alist
    else:
        for i in range(n):
            alist.append(a)
            a, b = b, a + b
        return alist

2.二分法

def func(alist, item):
    low = 0
    high 
= len(alist)-1 print(type(low)) n = 0 # 記錄查詢幾次查到 while low <= high: # 迴圈的次數小於或者等於high的時候停止迴圈 mid = int((low + high)/2) n += 1 # 沒查詢一次 查詢次數+1 if alist[mid]==item: # 比對中間值是否等於要查詢的引數 return mid # 如果是 直接返回值 if alist[mid]<item: # 判斷如果中間值小於要查詢得數
low = mid + 1 #那麼迴圈開始的數low 就等於 中間值+1 else: high = (mid-1) # 如果大於 就把中間值數的下標-1 縮小查詢範圍 return None #如果什麼都沒有查到 返回None print(func([1,2,33,4,58,9,11,12,19,18,89,20,28],28)) # 輸出查詢到的值

二分法 迭代查詢

def fun(alist,item):
    if len(alist) == 0:
        return False
    
else: mid = len(alist) // 2 #獲取中間值的下標 if item == alist[mid]: return True,item elif item < alist[mid]: # 如果查詢的數小於中間值 return fun(alist[:mid],item) #從開頭到中間值查詢 [:mid]是中間值66往前得數 else: return fun(alist[mid+1:],item) # 否則從中間值下一個數到結尾 # 輸出返回的值 print(fun([1, 22,33,44,55,66,77,88,99],66))

3.等邊三角形

for i in range(1,6):
    for j in range(1,6-i):
        print(" ",end="")
    for k in range(1,i+1):
        print("* ",end="")
    print("")

  等邊三角形二

for i in range(1,6):
    for j in range(1,6-i):
        print(" ",end="")
    print("* "*i)

4.直角三角形

for i in range(6):
  i += 1
  for j in range(i):
    print('*', end='')#end=‘'輸出空格
  print()

5.氣泡排序

def func(alist):
    for x in range(1,len(alist)):
        for i in range(0,len(alist)-x):
            if alist[i] > alist[i+1]:
                alist[i], alist[i+1] = alist[i+1], alist[i]
    return alist
print(func([1,4,2,3,6,7,8,9,0,5]))

6.選擇排序

def func(alist):
    for x in range(0,len(alist)):
        min_num = alist[x]
        for i in range(x+1,len(alist)):
            if alist[i] < min_num:
                alist[i], min_num = min_num, alist[i]
        alist[x] = min_num
    return alist
print(func([1,4,2,3,6,7,8,9,0,5]))

7.連結串列

class Node:
    def __init__(self, initdata):
        self.__data = initdata
        self.__next = None

    def getData(self):
        return self.__data

    def getNext(self):
        return self.__next

    def setData(self, newdata):
        self.__data = newdata

    def setNext(self, newnext):
        self.__next = newnext

class SinCycLinkedlist:
    def __init__(self):
        self.head = Node(None)
        self.head.setNext(self.head)

    def add(self, item):
        temp = Node(item)
        temp.setNext(self.head.getNext())
        self.head.setNext(temp)

    def remove(self, item):
        prev = self.head
        while prev.getNext() != self.head:
            cur = prev.getNext()
            if cur.getData() == item:
                prev.setNext(cur.getNext())
            prev = prev.getNext()

    def search(self, item):
        cur = self.head.getNext()
        while cur != self.head:
            if cur.getData() == item:
                return True
            cur = cur.getNext()

        return False

    def empty(self):
        return self.head.getNext() == self.head

    def size(self):
        count = 0
        cur = self.head.getNext()
        while cur != self.head:
            count += 1
            cur = cur.getNext()

        return count

if __name__ == '__main__':
    s = SinCycLinkedlist()
    print('s.empty() == %s, s.size() == %s' % (s.empty(), s.size()))

    s.add(19)
    s.add(86)
    print('s.empty() == %s, s.size() == %s' % (s.empty(), s.size()))

    print('86 is%s in s' % ('' if s.search(86) else ' not',))
    print('4 is%s in s' % ('' if s.search(4) else ' not',))
    print('s.empty() == %s, s.size() == %s' % (s.empty(), s.size()))

    s.remove(19)
    print('s.empty() == %s, s.size() == %s' % (s.empty(), s.size()))

8.青蛙跳臺階:

  一隻青蛙一次可以跳上1級臺階,也可以跳上2級……它也可以跳上n級。求該青蛙跳上一個n級的臺階總共有多少種跳法。

#! /usr/bin/env python
# -*- coding: utf-8 -*-
def quick(list):
    if len(list) < 2:
        return list

    tmp = list[0]  # 臨時變數 可以取隨機值
    left = [x for x in list[1:] if x <= tmp]  # 左列表
    right = [x for x in list[1:] if x > tmp]  # 右列表
    return quick(left) + [tmp] + quick(right)

li = [4,3,7,5,8,2]
print quick(li)  # [2, 3, 4, 5, 7, 8]

#### 對[4,3,7,5,8,2]排序
'''
[3, 2] + [4] + [7, 5, 8]                 # tmp = [4]
[2] + [3] + [4] + [7, 5, 8]              # tmp = [3] 此時對[3, 2]這個列表進行排序
[2] + [3] + [4] + [5] + [7] + [8]        # tmp = [7] 此時對[7, 5, 8]這個列表進行排序
'''