Cisco Packet Tracer 7.2.1 Installation on Ubuntu 18.04 LTS Linux

Cisco Packet Tracer v7.2.1 was released in mid 2018, which doesn’t appear to need libicui18n.so.52 unlike CPT v7.1 (The bug was fixed in the latest release and v7.2.1 runs without any issue on Ubuntu 16.04). However, CPT v7.2.1 on Ubuntu 18.04 is unable to locate libpng12. Following solution (QT Libraries, libcu52 and libpng12 installation) fixed it for me:

Install Qt libraries:

sudo apt install libqt5webkit5 libqt5multimediawidgets5 libqt5svg5 libqt5script5 libqt5scripttools5 libqt5sql5

Install libcu52:

wget http://mirrors.kernel.org/ubuntu/pool/main/i/icu/libicu52_52.1-3ubuntu0.8_amd64.deb
sudo dpkg -i libicu52_52.1-3ubuntu0.8_amd64.deb

Install libpng12:

wget http://ftp.debian.org/debian/pool/main/libp/libpng/libpng12-0_1.2.50-2+deb8u3_amd64.deb
sudo dpkg -i libpng12-0_1.2.50-2+deb8u3_amd64.deb

Now, CPT should start correctly via 'packettracer' command in terminal.

Credits: 
Stack Exchange