太久不編程,手會生。最近開始做一些編程題目,用我比較不熟悉的python來寫。
Two Sum(題目來自:https://oj.leetcode.com/problems/two-sum/)
Given an array of integers, find two numbers such that they add up to a specific target number.
Please note that your returned answers (both index1 and index2) are not zero-based.
You may assume that each input would have exactly one solution.
Input: numbers={2, 7, 11, 15}, target=9
Output: index1=1, index2=2
下面是我的解答(Accepted):
class Solution:
# @return a tuple, (index1, index2)
def twoSum(self, num, target):
newMap = {}
for i in range(len(num)):
val = target - num[i]
if val in newMap:
return (newMap[val], i+1)
else:
newMap[num[i]] = i + 1
說明:
1) LeetCode 這一題的標註難度是Easy。確實也比較簡單;
2)求a + b = target。 我的思路就是構造一個字典,每次檢查 target - x 是否在字典裏,若不是則把x加入字典。python 對字典的原生支持使得實現非常輕鬆。