遞歸，劃分和征服最大子陣列

Question

我似乎無法弄清楚爲什麼我在下面突出顯示的行上編譯時出現錯誤消息。該錯誤信息是「ValueError異常：需要比2點的值更解壓」 ...預先感謝您的幫助

def divConHelper(array, first, center, last): 
    sumRight = float('-inf') #assign impossibly low number 
    sumLeft = float('-inf') #assign impossibly low number 
    leftIndexMax = 0 
    rightIndexMax = 0 

    # Determine crossover max toward left 
    currentLTotal = 0 
    for i in range(first, center): 
    #Incrementally add values to sum 
     currentLTotal += sum(array[i:center-1]) 
    #if the total is greater than the sumLeft, replace 
     if currentLTotal > sumLeft: 
     sumLeft = currentLTotal 
     leftIndexMax = i 

    # Determine crossover max toward right 
    currentRTotal=0 
    for i in range(center+1, last): 
    #Incrementally add values to sum 
     currentRTotal += sum(array[center:i+1]) 
    #if the rightTotal is greater than the sumRight, replace 
     if currentRTotal > sumRight: 
     sumRight = currentRTotal 
     rightIndexMax = i+1 

    bothTotal = sumRight + sumLeft 

    return(leftIndexMax, rightIndexMax, bothTotal) 
    #return(bothTotal) 

def divConMaxSub(self, array, first, last): 

    if (last-first) == 0: 
     return array[first: last +1], array[0] 


    center = (first+last)// 2 
    #Recursive calls to divConMaxSub 
    (minA, maxA, sumA) = self.divConMaxSub(array, first, center) 
    (minB, maxB, sumB) = self.divConMaxSub(array, center+1, last) 
    #call to get max cross values 
    (maxL, maxR, maxCross) = divConHelper(array, first, center, last) 

    #Calulate the max subarray value 
    finalMax = max(sumA, sumB, maxCross) 
    #Logic block for return values 
    if (finalMax == sumA): 
     return array[minA: maxA], sumA 
     #return minA, maxA, sumA 
    elif (finalMax == sumB): 
     return array[minB: maxB], sumB 
     #return minB, maxB, sumB 
    elif (finalMax == maxCross): 
     return array[maxL: maxR], maxCross 
     #return maxL, maxR, maxCross 

這裏是我主要的代碼

from array import * 
from utilities import utilities 
from algorithms import algorithms 
def main(): 
    utils = utilities() 
    alg = algorithms() 
    results = utils.load() 
    for line in results: 
    max_sub_array, max_sum = alg.simpleenumeration(line) 
    utils.printtofile("Simple Enumeration", max_sub_array, max_sum) 
    max_sub_array, max_sum = alg.betterenumeration(line) 
    utils.printtofile("Better Enumeration", max_sub_array, max_sum) 
    max_sub_array, max_sum = alg.divConMaxSub(line) 
    utils.printtofile("Divide and Conquer", max_sub_array, max_sum) 
    max_sub_array, max_sum = alg.linear_sub_array(line) 
    utils.printtofile("Linear sub array", max_sub_array, max_sum) 
    # print("--------------------") 

main() 

Answer 1

本聲明：

return array[minA: maxA], sumA 

不返回三個參數（如你似乎在此代碼預計）：

(minA, maxA, sumA) = self.divConMaxSub(array, first, center) 

它返回一個數組的塊作爲第一個參數，總和作爲第二個參數。因此，Python抱怨說無法使用divConMaxSub的輸出來初始化左側的三個值，因爲右側只有兩個值可用。