From career up 150.

Implement an algorithm to print all valid (e.g., properly opened and closed) combinations of n-pairs of parentheses.

#include <iostream>
using namespace std;

const int n = 3;
char a[n * 2];

void print(int l, int r, int i) {
	if(l < 0 || r < l){
		return;
	}
	if (l==0 && r==0) {
		for (int j = 0; j < n * 2; j++) {
			cout << a[j] << " ";
		}
		cout << endl;
	} else {
		if (l > 0) {
			a[i] = '(';
			print(l - 1, r, i + 1);
		}
		if (r > l) {
			a[i] = ')';
			print(l, r - 1, i + 1);
		}
	}
}

int main() {
	print(3, 3, 0);
}
 

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