Day 4 Review:
https://leetcode.com/problems/find-players-with-zero-or-one-losses/
呢題應該都相對簡單,我地整兩個dictionary,一個dictionary係keep track住每個player贏過幾多場,另外一個dictionary係keep track住每個player輸過幾多場
answer[0]就係出現過係winner dictionary but not dictionary
answer[1]就係loser dictionary嘅value係1
最後兩個都 answer[0].sort(), answer[1].sort() 就ok
https://leetcode.com/problems/word-subsets/
呢題比較難,做一個Time Limit Exceeded 示範:
我地如果每一隻word1都要compare曬每一隻word2,就要做len(words1) * len(words2) comparison,會太慢
leetcode medium開始就要慢慢做一啲observation,呢題你要observe到我地只需要知道每一個英文字母係words2嘅每一隻字最多出現幾多次
例如 ["picnic", "ice"] ,picnic入面 'i' 出現左兩次, ice入面個'i'出現左一次,如果一個字符合picnic 出現兩次 i,咁佢一定會符合ice出現一次i,同樣地c都係,要符合條件一定要有最少兩個c (picnic)
所以要符合條件就要有 p : 1, i : 2, c : 2, n: 1, e: 1
答案你可以睇discussion