这个C语言代码的结果有什么解释？

This is a problem on my Computer Science final study guide. The correct answer is x[2] = 7 and x[4] = 4. When I tried interpreting the code it seemed like the value of x[2] wasn't even changed by the sort function. But it was! Could someone explain why x[2] = 7 and x[4] = 4? Thank you!This is a problem on my Computer Science final