Delete Columns to Make Sorted

class Solution {
    public int minDeletionSize(String[] strs) {
        // O(m*n)
        int len = strs[0].length();
        int ans = 0;

        for(int i=0; i<len; i++) {
            for(int j=1; j<strs.length; j++) {
                if(strs[j].charAt(i) < strs[j-1].charAt(i)) {
                    ans++;
                    break;
                }
            }
        }

        return ans;
    }
}