1996. The Number of Weak Characters in the Game | leetcode solution

 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

solution :

class Solution {

public:

    bool static sort_first(vector<int>&a , vector<int>&b )

    {   

        if(a[0] == b[0])

            return a[1] > b[1];

        return a[0] < b[0];

    }

    int numberOfWeakCharacters(vector<vector<int>>& properties) {

       

          int count = 0;

         sort(properties.begin() , properties.end() , sort_first);

        int n = properties.size();

        int max_num = properties[n-1][1];

        for(int i =n-1 ; i >= 0 ; i--)

        {

                if(properties[i][1] < max_num )

                    count++;

                else

                    if(properties[i][1] > max_num)

                        max_num = properties[i][1];

        }

        return count;

        

    }

};

references : https://leetcode.com/problems/the-number-of-weak-characters-in-the-game/