Answer 1

Let's see what happen at every recursion step :-

func(5) { 5>0 true so call func(4) first}
func(4) { 4>0 true so call func(3) first}
.
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func(1) { 1>0 true so call func(0) first}
func(0) { 0>0 false so skip the stuff in *if* statement and backtrack }

back to func(1)'s cout statement which displays value of "x" that is decremented to 0 here.

Again backtrack

Display 1, as new value of "x" is 1 and again backtrack

similarly display 2 and so on
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.
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Final output = 01234