Python中斷/返回子集總和的遞歸函數

Question

我正在嘗試實現此功能，以查找任何子集的總和是否等於目標值：

def subset_sum(numbers, target, partial=[]):
    s = sum(partial)

    # check if the partial sum is equals to target
    if s == target: 
        print "sum(%s)=%s" % (partial, target)
    if s >= target:
        return  # if we reach the number why bother to continue

    for i in range(len(numbers)):
        n = numbers[i]
        remaining = numbers[i+1:]
        subset_sum(remaining, target, partial + [n]) 

但是，我希望一旦遇到目標實例，該函數就可以“中斷” /返回，這樣它就不會繼續尋找更多對象。

我已經嘗試過了，但是仍然繼續：

def subset_sum(numbers, target, partial=[]):
    s = sum(partial)

    # check if the partial sum is equals to target
    if s == target: 
        print "sum(%s)=%s" % (partial, target)
        return   // should stop once reaches one instance
    if s >= target:
        return  # if we reach the number why bother to continue

    for i in range(len(numbers)):
        n = numbers[i]
        remaining = numbers[i+1:]
        subset_sum(remaining, target, partial + [n]) 

Answer 1

使subset_sum返回布爾值：是否找到該子集。 檢查遞歸調用的結果。

def subset_sum(numbers, target, partial=[]):
    s = sum(partial)

    # check if the partial sum is equals to target
    if s == target: 
        print "sum(%s)=%s" % (partial, target)
        return True   # should stop once reaches one instance
    if s > target:
        return False # if we reach the number why bother to continue

    for i in range(len(numbers)):
        n = numbers[i]
        remaining = numbers[i+1:]
        if subset_sum(remaining, target, partial + [n]):
            return True
    return False

更好的方法可能是返回答案（即partial答案）或None 。

Answer 2

編輯：錯過了原始算法，這應該返回第一個有效列表。

嘗試這個：

def subset_sum(numbers, target, partial=[]): 
    s = sum(partial) # check if the partial sum is equals to target 
    if s >= target: # if we reach the number why bother to continue 
        return partial
    for i in range(len(numbers)):
        n = numbers[i]
        remaining = numbers[i+1:]
        results = subset_sum(remaining, target, partial + [n])
        if results:
            return results