(may also work for J730F, see post #3)
This procedure has been tested on J730GMDXU1AQF8 firmware. It may work for future releases or it may not.
If an updated firmware becomes available my advice is to update with FLASHFIRE to maintain root.
DISCLAIMER: YOU FLASH THESE AT YOUR OWN RISK. THE KNOX COUNTER WILL BE TRIPPED AND WILL POTENTIALLY VOID YOUR WARANTY. HAVING THE STOCK FIRMWARE TO HAND IS ALSO ADVISED
NOTE: BEFORE MAKING MODIFICATIONS, ON SOME ANDROID 5.1.1/6.0/7.0 DEVICES IT IS NECESSARY TO GO TO:
Settings -> Developer Options -> OEM unlocking
AND ENABLE OEM UNLOCK FIRST OR YOU MAY ENCOUNTER 'BLOCKED BY FRP LOCK' WHEN FLASHING.
◘ 1. Download the files below:
◘ 2. Install the USB driver and ODIN to Windows.
◘ 3. Boot your device to RECOVERY mode then select FACTORY RESET. THIS WILL WIPE YOUR DEVICE AND YOU WILL LOSE ALL DATA. (This procedure is required to remove encryption or your device won't boot)
◘ 4. From RECOVERY, IMMEDIATELY Boot your device to DOWNLOAD mode then connect your USB cable. (DO NOT LET YOUR DEVICE REBOOT NORMALLY OR YOUR DEVICE WILL RE-ENCRYPT)
◘ 5. Run ODIN and place the sm-j730gm_SR3-SuperSU-v2.79-SR3_root_boot_32.tar file as is in the AP slot. Don't change any options and hit START.
◘ 6. Wait for the device to flash and reboot.
◘ 7. Install the SuperSU apk from Play store and you should be rooted.
◘ 8. Have fun!
Credits: Me, @Chainfire(for supersu), @mottx(for testing)
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