README_EN.md

1738. Find Kth Largest XOR Coordinate Value

中文文档

Description

You are given a 2D matrix of size m x n, consisting of non-negative integers. You are also given an integer k.

The value of coordinate (a, b) of the matrix is the XOR of all matrix[i][j] where 0 <= i <= a < m and 0 <= j <= b < n (0-indexed).

Find the kth largest value (1-indexed) of all the coordinates of matrix.

 

Example 1:

Input: matrix = [[5,2],[1,6]], k = 1
Output: 7
Explanation: The value of coordinate (0,1) is 5 XOR 2 = 7, which is the largest value.

Example 2:

Input: matrix = [[5,2],[1,6]], k = 2
Output: 5
Explanation: The value of coordinate (0,0) is 5 = 5, which is the 2nd largest value.

Example 3:

Input: matrix = [[5,2],[1,6]], k = 3
Output: 4
Explanation: The value of coordinate (1,0) is 5 XOR 1 = 4, which is the 3rd largest value.

 

Constraints:

• m == matrix.length
• n == matrix[i].length
• 1 <= m, n <= 1000
• 0 <= matrix[i][j] <= 106
• 1 <= k <= m * n

Solutions

Python3

class Solution:
    def kthLargestValue(self, matrix: List[List[int]], k: int) -> int:
        m, n = len(matrix), len(matrix[0])
        s = [[0] * (n + 1) for _ in range(m + 1)]
        ans = []
        for i in range(m):
            for j in range(n):
                s[i + 1][j + 1] = s[i + 1][j] ^ s[i][j + 1] ^ s[i][j] ^ matrix[i][j]
                ans.append(s[i + 1][j + 1])
        return nlargest(k, ans)[-1]

Java

class Solution {

    public int kthLargestValue(int[][] matrix, int k) {
        int m = matrix.length, n = matrix[0].length;
        int[][] s = new int[m + 1][n + 1];
        List<Integer> ans = new ArrayList<>();
        for (int i = 0; i < m; ++i) {
            for (int j = 0; j < n; ++j) {
                s[i + 1][j + 1] = s[i + 1][j] ^ s[i][j + 1] ^ s[i][j] ^ matrix[i][j];
                ans.add(s[i + 1][j + 1]);
            }
        }
        Collections.sort(ans);
        return ans.get(ans.size() - k);
    }
}

C++

class Solution {
public:
    int kthLargestValue(vector<vector<int>>& matrix, int k) {
        int m = matrix.size(), n = matrix[0].size();
        vector<vector<int>> s(m + 1, vector<int>(n + 1));
        vector<int> ans;
        for (int i = 0; i < m; ++i) {
            for (int j = 0; j < n; ++j) {
                s[i + 1][j + 1] = s[i + 1][j] ^ s[i][j + 1] ^ s[i][j] ^ matrix[i][j];
                ans.push_back(s[i + 1][j + 1]);
            }
        }
        sort(ans.begin(), ans.end());
        return ans[ans.size() - k];
    }
};

Go

func kthLargestValue(matrix [][]int, k int) int {
	m, n := len(matrix), len(matrix[0])
	s := make([][]int, m+1)
	for i := range s {
		s[i] = make([]int, n+1)
	}
	var ans []int
	for i := 0; i < m; i++ {
		for j := 0; j < n; j++ {
			s[i+1][j+1] = s[i+1][j] ^ s[i][j+1] ^ s[i][j] ^ matrix[i][j]
			ans = append(ans, s[i+1][j+1])
		}
	}
	sort.Ints(ans)
	return ans[len(ans)-k]
}

...