1996. The Number of Weak Characters in the Game

Medium

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You are playing a game that contains multiple characters, and each of the characters has two main properties: attack and defense. You are given a 2D integer array properties where properties[i] = [attacki, defensei] represents the properties of the ith character in the game.

A character is said to be weak if any other character has both attack and defense levels strictly greater than this character's attack and defense levels. More formally, a character i is said to be weak if there exists another character j where attackj > attacki and defensej > defensei.

Return the number of weak characters.

Example 1:

Input: properties = [[5,5],[6,3],[3,6]]
Output:
 0
Explanation:
 No character has strictly greater attack and defense than the other.

Example 2:

Input: properties = [[2,2],[3,3]]
Output:
 1
Explanation:
 The first character is weak because the second character has a strictly greater attack and defense.

Example 3:

Input: properties = [[1,5],[10,4],[4,3]]
Output:
 1
Explanation:
 The third character is weak because the second character has a strictly greater attack and defense.

Constraints:

• 2 <= properties.length <= 105

• properties[i].length == 2

• 1 <= attacki, defensei <= 105

from functools import cmp_to_key
class Solution:
    def numberOfWeakCharacters(self, properties: List[List[int]]) -> int:
        properties.sort(key=lambda x: (-x[0],x[1]))
        count = 0
        curr_max = 0
        for _, d in properties:
            if d < curr_max:
                count += 1
            else:
                curr_max = d
        return count