By "King Zheng", do you mean the man who later became the first Emperor? I don't think there was a state called Wu in the Warring States period (I take it that you mean the period startting from about 500BC to 221BC), unless you mean the one in the Spring and Autumn period (that's the one right before the Warring States, from about 770BC to about 500BC), which was actually conquered by the state of Yue (not by any King Zheng) in 478BC.