💙 【2133】Check if Every Row and Column Contains All Numbers easy

An n x n matrix is valid if every row and every column contains all the integers from 1 to n (inclusive).

Given an n x n integer matrix matrix, return true if the matrix is valid. Otherwise, return false.

Example 1:

Input: matrix = [[1,2,3],[3,1,2],[2,3,1]]
Output: true
Explanation: In this case, n = 3, and every row and column contains the numbers 1, 2, and 3.
Hence, we return true.

Example 2:

Input: matrix = [[1,1,1],[1,2,3],[1,2,3]]
Output: false
Explanation: In this case, n = 3, but the first row and the first column do not contain the numbers 2 or 3.
Hence, we return false.

Constraints:

• n == matrix.length == matrix[i].length
• 1 <= n <= 100
• 1 <= matrix[i][j] <= n

📝个人分析

如果每一行和每一列包含从1到n（包括1到n）的所有整数，则nxn矩阵有效。 给定一个nxn整数矩阵，如果该矩阵有效，则返回true。否则，返回false。

矩阵行列相等，按照常规循环。这里使用HashSet来记录是否存在重复值。Set不会存入相同的内容，每次循环检查set长度是否与矩阵行或者列相等。

💡Solution

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  public boolean checkValid(int[][] matrix) {
        int n = matrix.length;
        for(int i = 0;i<n;i++){
            Set<Integer> row = new HashSet<>();
            Set<Integer> col = new HashSet<>();
            for(int j = 0;j<n;j++){
                row.add(matrix[i][j]);
                col.add(matrix[j][i]);
            }
            if(row.size() != n || col.size() != n)return false;
        }
        return true;
    }

🔗 Refer links

https://leetcode.com/problems/check-if-every-row-and-column-contains-all-numbers/