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#944 - Delete Columns to Make Sorted

Problem Description

You are given an array of n strings strs, all of the same length.

The strings can be arranged such that there is one on each line, making a grid.

For example, strs = ["abc", "bce", "cae"] can be arranged as follows:

  • abc
  • bce
  • cae

You want to delete the columns that are not sorted lexicographically. In the above example (0-indexed), columns 0 ('a', 'b', 'c') and 2 ('c', 'e', 'e') are sorted, while column 1 ('b', 'c', 'a') is not, so you would delete column 1.

Return the number of columns that you will delete.

Solution

/**
 * @param {string[]} strs
 * @return {number}
 */
var minDeletionSize = function(strs) {
  let result = 0;

  for (let col = 0; col < strs[0].length; col++) {
    for (let row = 1; row < strs.length; row++) {
      if (strs[row][col] < strs[row - 1][col]) {
        result++;
        break;
      }
    }
  }

  return result;
};