Problem:
Implement an algorithm to print all valid (e.g., properly opened and closed) combinations of n-pairs of parentheses.
给定一个正整数N,打印所有可能的N对括号序列,例子如下。
EXAMPLE:
input: 3 (e.g., 3 pairs of parentheses)
output: ()()(), ()(()), (())(), ((()))
My Code:
public class Parenthese {
public static void printParentheses(int n){
printSub(n, 0, 0, "");
}
public static void printSub(int n, int l, int r, String s){
if(l == n && r == n){
System.out.println("One result:" + s);
return;
}else {
if(l > r){
if(l < n) {
String s1 = s + '(';
printSub(n, l+1, r, s1);
}
String s2 = s+ ')';
printSub(n, l, r+1, s2);
}
if(l == r){
if(l<n){
String s1 = s + '(';
printSub(n, l+1, r, s1);
}
}
}
}
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
printParentheses(4);
}
}
One result:(((())))
One result:((()()))
One result:((())())
One result:((()))()
One result:(()(()))
One result:(()()())
One result:(()())()
One result:(())(())
One result:(())()()
One result:()((()))
One result:()(()())
One result:()(())()
One result:()()(())
One result:()()()()