如何在Python中使用迭代加深搜索算法进行查找

# IDS algorithm to search for a target string in a given string
def iterative_deepening_search(target, string):
    max_depth = len(string)
    for depth in range(1, max_depth+1):
        result = dfs(target, string, depth, 0)
        if result != None:
            return True
    return False

# DFS algorithm to search for a target string in a given string within a certain depth
def dfs(target, string, max_depth, current_depth):
    if current_depth == max_depth:
        return None
    for i in range(len(string)-len(target)+1):
        if string[i:i+len(target)] == target:
            return i
        result = dfs(target, string[i+1:], max_depth, current_depth+1)
        if result != None:
            return result+i+1
    return None

# test the algorithm
string = "pidancode.com"
target1 = "pidan"
target2 = "picode"
target3 = "pidancode.com"
target4 = "皮蛋编程"

print(iterative_deepening_search(target1, string)) # expected output: True
print(iterative_deepening_search(target2, string)) # expected output: False
print(iterative_deepening_search(target3, string)) # expected output: True
print(iterative_deepening_search(target4, string)) # expected output: False