flow of the recursion

Parents : Working of Recursion

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Understand the concept of Call Stack before reading this.

Example: To get the grip on how recursion flows, we can see the two following functions

Function 1 (Print reverse array of numbers from n to 1)

First printing is done and then recursive calls are made.

Here we assume/hypothesize that the function will work for n-1 and will give us the result for n-1 value i.e
solve(n-1) will give us 4 , 3 , 2 , 1 Thus what left is to induct the last value i.e 5 for that we put the condition cout<<i before the hypothesis part.

void solve(i){
	
	 if(i==0)  // Base condition
		 return ;
	 cout<<i; // induction 
	 solve(i-1);// hypothesis
	 
}
int main(){
	solve(5);
}

Output

5 , 4 , 3 , 2 , 1

Function 2 ( Print array of numbers from 1 to n)

First recursive calls are made and then printing is done.

Here we assume/hypothesize that the function solve will work for n-1 and will give us the result for n-1 value i.e
solve(n-1) will give us 1 , 2 , 3 , 4
Thus what left is to induct the last value i.e 5 for that we put the condition cout<<i after the hypothesis.

void solve(i){
	
	 if(i==0)  // Base condition
		 return ;
	 cout<<i;  // induction 
	 solve(i-1); // hypothesis 
	 
}
int main(){
	solve(5);
}

Output

1 , 2 , 3 , 4 , 5

Illustrations

References

Footnotes