README.md

1996. The Number of Weak Characters in the Game

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

Solutions (Rust)

1. Solution

impl Solution {
    pub fn number_of_weak_characters(mut properties: Vec<Vec<i32>>) -> i32 {
        let mut max_defense = 0;
        let mut ret = 0;

        properties.sort_unstable_by_key(|p| (-p[0], p[1]));

        for p in &properties {
            ret += (max_defense > p[1]) as i32;
            max_defense = max_defense.max(p[1]);
        }

        ret
    }
}