#!/bin/bash
while read -r dir
do
    last_file=$(ls -ht -- "${dir}" | head -n1)
    last_file_time=$(stat -c %Y -- "${last_file}")
    last_file_time_formated=$(date -d "@${last_file_time}" +%Y%m%d%H%M.%S)
    touch -a -m -t "${last_file_time_formated}" -- "${dir}"
done <<< "$(find . -mindepth 1 -maxdepth 1 -type d)"