如何使用 Python 在列表中查找特定数字的总和

Question

我有一个数字列表：

[40.5, 19.04, 31.72, 68.16, 45.68, 45.68, 532.74, 137.52, 401.58, 25.92, 185.90, 1037.96, 23.41, 829.50, 98.35, 57.12, 620.87, 21, 435.08, 460.85, 1079.16, 1386.29, 272.82, 131.44, 135.51, 39, 1079.16, 230.63, 1297.44, 301.27, 372.57,173.17, 191.84, 213.92, 423.9, 56.24, 189.98, 14.76]

我在列表中有一些特定数字的总和，我如何得到已知总和的数字？

例如，如果知道总和是 59.04，我如何找出 40.5 和 19.04？

干杯!

Answer 1

使用它来查找和对

def findPair(A, sum):
    for i in range(len(A) - 1):# consider each element except last element
        for j in range(i + 1, len(A)):# start from i'th element till last element
            if A[i] + A[j] == sum:# if desired sum is found, print it and return
                print("Pair found at index", i, "and", j)
                print("Sum Pair:", A[i], A[j])
                return
    print("Pair not found")# No pair with given sum exists in the list
 
 
A = [40.5, 19.04, 31.72, 68.16, 45.68, 45.68, 532.74, 137.52, 401.58, 25.92, 185.90, 1037.96, 23.41, 829.50, 98.35, 57.12, 620.87, 21, 435.08, 460.85, 1079.16, 1386.29, 272.82, 131.44, 135.51, 39, 1079.16, 230.63, 1297.44, 301.27, 372.57,173.17, 191.84, 213.92, 423.9, 56.24, 189.98, 14.76]

findPair(A, 59.54)
sum = 99.88
findPair(A, sum)

Output：

Pair found at index 0 and 1
Sum Pair: 40.5 19.04
Pair found at index 2 and 3
Sum Pair: 31.72 68.16

参考： https://www.techiedelight.com/find-pair-with-given-sum-array/

N 个数字的总和：

import itertools
def findlist(A, summ):
    for i in range(len(A)):
        for j in itertools.combinations(A, i):
            res = round(sum(list(j)), 2) 
            if res == summ:
                print("Sum Combinations", j )
A = [40.5, 19.04, 31.72, 68.16, 45.68]
findlist(A, 91.26)

注意：对于大型列表，这会比较慢

Answer 2

is_sum = lambda seq, x: any(x == y + z for yi, y in enumerate(seq) for zi, z in enumerate(seq) if zi != yi)

>>> is_sum([40.5, 19.04, 31.72, 68.16, 45.68, 45.68, 532.74, 137.52, 401.58, 25.92, 185.90, 1037.96, 23.41, 829.50, 98.35, 57.12, 620.87, 21, 435.08, 460.85, 1079.16, 1386.29, 272.82, 131.44, 135.51, 39, 1079.16, 230.63, 1297.44, 301.27, 372.57,173.17, 191.84, 213.92, 423.9, 56.24, 189.98, 14.76], 59.04)
True

Answer 3

只需使用 itertools，

import itertools
listofnumbers = [40.5, 19.04, 31.72, 68.16, 45.68, 45.68, 532.74, 137.52, 401.58, 25.92, 185.90, 1037.96, 23.41, 829.50, 98.35, 57.12, 620.87, 21, 435.08, 460.85, 1079.16, 1386.29, 272.82, 131.44, 135.51, 39, 1079.16, 230.63, 1297.44, 301.27, 372.57,173.17, 191.84, 213.92, 423.9, 56.24, 189.98, 14.76]
target = 59.54
for numbers in itertools.combinations(listofnumbers,2):
    if round(sum(numbers),2) == target:
        print(numbers)

指定 2 个数字，您的 output 将是

(40.5, 19.04)