LeetCode-in-All

74. Search a 2D Matrix

Medium

Write an efficient algorithm that searches for a value in an m x n matrix. This matrix has the following properties:

• Integers in each row are sorted from left to right.
• The first integer of each row is greater than the last integer of the previous row.

Example 1:

Input: matrix = [[1,3,5,7],[10,11,16,20],[23,30,34,60]], target = 3

Output: true

Example 2:

Input: matrix = [[1,3,5,7],[10,11,16,20],[23,30,34,60]], target = 13

Output: false

Constraints:

• m == matrix.length
• n == matrix[i].length
• 1 <= m, n <= 100
• -104 <= matrix[i][j], target <= 104

Solution

# @param {Integer[][]} matrix
# @param {Integer} target
# @return {Boolean}
def search_matrix(matrix, target)
  end_col = matrix[0].length
  target_row = 0
  result = false

  matrix.each_with_index do |row, i|
    if row[end_col - 1] >= target
      target_row = i
      break
    end
  end

  matrix[target_row].each_with_index do |element, i|
    if element == target
      result = true
      break
    end
  end

  return result
end

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