The Number of Weak Characters in the Game

Problem Statement - link #

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.

Examples #

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 <= 10^5
• properties[i].length == 2
• 1 <= attacki, defensei <= 10^5

Solutions #

    class Solution {
    public:
        static bool sort2(const vector<int> &a, const vector<int> &b){
            if(a[0]!=b[0])
                return a[0]>b[0];
            return a[1] < b[1];
        }
        int numberOfWeakCharacters(vector<vector<int>>& p) {
            sort(p.begin(),p.end(),sort2);
            int maxV = INT_MIN;
            int res=0;
            for(auto i: p){
                if(maxV > i[1]) res++;
                else maxV = i[1];
            }
            return res;
        }
};