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LeetCode 221. Maximal Square (javascript solution)

codingpineapple
・1 min read

Description:

Given an m x n binary matrix filled with 0's and 1's, find the largest square containing only 1's and return its area.

Solution:

Time Complexity : O(n^2)
Space Complexity: O(n^2)

var maximalSquare = function(matrix) {
        const rows = matrix.length, cols = rows > 0 ? matrix[0].length : 0;
        // Create dp array
        const dp = Array(rows + 1).fill(0).map(() => Array(cols + 1).fill(0));

        // Keep trac of the max square length
        let maxsqlen = 0;
        for (let i = 1; i <= rows; i++) {
            for (let j = 1; j <= cols; j++) {
                // Only check cells that have a 1 in the original array
                if (matrix[i-1][j-1] == '1'){
                    // Check if the current cell is part of a square
                    dp[i][j] = Math.min(Math.min(dp[i][j - 1], dp[i - 1][j]), dp[i - 1][j - 1]) + 1;
                    maxsqlen = Math.max(maxsqlen, dp[i][j]);
                }
            }
        }
        // Return the area of the square
        return maxsqlen * maxsqlen;
};
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