1996. The Number of Weak Characters in the Game

Description

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

Solution 1

Python Code
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class Solution:
    def numberOfWeakCharacters(self, properties: List[List[int]]) -> int:
        properties.sort(key=lambda x: (-x[0], x[1]))
        ans = mx = 0
        for _, x in properties:
            ans += x < mx
            mx = max(mx, x)
        return ans

Java Code
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class Solution {
    public int numberOfWeakCharacters(int[][] properties) {
        Arrays.sort(properties, (a, b) -> b[0] - a[0] == 0 ? a[1] - b[1] : b[0] - a[0]);
        int ans = 0, mx = 0;
        for (var x : properties) {
            if (x[1] < mx) {
                ++ans;
            }
            mx = Math.max(mx, x[1]);
        }
        return ans;
    }
}

C++ Code
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class Solution {
public:
    int numberOfWeakCharacters(vector<vector<int>>& properties) {
        sort(properties.begin(), properties.end(), [&](auto& a, auto& b) { return a[0] == b[0] ? a[1] < b[1] : a[0] > b[0]; });
        int ans = 0, mx = 0;
        for (auto& x : properties) {
            ans += x[1] < mx;
            mx = max(mx, x[1]);
        }
        return ans;
    }
};

Go Code
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func numberOfWeakCharacters(properties [][]int) (ans int) {
	sort.Slice(properties, func(i, j int) bool {
		a, b := properties[i], properties[j]
		if a[0] == b[0] {
			return a[1] < b[1]
		}
		return a[0] > b[0]
	})
	mx := 0
	for _, x := range properties {
		if x[1] < mx {
			ans++
		} else {
			mx = x[1]
		}
	}
	return
}

TypeScript Code
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function numberOfWeakCharacters(properties: number[][]): number {
    properties.sort((a, b) => (a[0] == b[0] ? a[1] - b[1] : b[0] - a[0]));
    let ans = 0;
    let mx = 0;
    for (const [, x] of properties) {
        if (x < mx) {
            ans++;
        } else {
            mx = x;
        }
    }
    return ans;
}

JavaScript Code
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/**
 * @param {number[][]} properties
 * @return {number}
 */
var numberOfWeakCharacters = function (properties) {
    properties.sort((a, b) => (a[0] == b[0] ? a[1] - b[1] : b[0] - a[0]));
    let ans = 0;
    let mx = 0;
    for (const [, x] of properties) {
        if (x < mx) {
            ans++;
        } else {
            mx = x;
        }
    }
    return ans;
};