python算法代码

以下是几种常见的Python算法代码示例：

1. 查找算法 - 二分查找

def binary_search(arr, target):
    low = 0
    high = len(arr) - 1
    
    while low <= high:
        mid = (low + high) // 2
        if arr[mid] == target:
            return mid
        elif arr[mid] < target:
            low = mid + 1
        else:
            high = mid - 1
    
    return -1

2. 排序算法 - 冒泡排序

def bubble_sort(arr):
    n = len(arr)
    
    for i in range(n):
        for j in range(0, n-i-1):
            if arr[j] > arr[j+1]:
                arr[j], arr[j+1] = arr[j+1], arr[j]

3. 递归算法 - 斐波那契数列

def fibonacci(n):
    if n <= 0:
        return 0
    elif n == 1:
        return 1
    else:
        return fibonacci(n-1) + fibonacci(n-2)

4. 动态规划算法 - 最长递增子序列

def longest_increasing_subsequence(arr):
    n = len(arr)
    dp = [1] * n
    
    for i in range(1, n):
        for j in range(i):
            if arr[i] > arr[j]:
                dp[i] = max(dp[i], dp[j] + 1)
    
    return max(dp)

5. 贪心算法 - 零钱兑换问题

def coin_change(coins, amount):
    coins.sort(reverse=True)
    count = 0
    
    for coin in coins:
        count += amount // coin
        amount = amount % coin
    
    if amount != 0:
        return -1
    else:
        return count