实现一种算法,打印n对括号的全部有效组合(即左右括号正确配对)。
示例
输入:3
输出:((())),(()()),(())(),()(()),()()()。
import java.util.ArrayList;
public class CCI_9_6 {
public static ArrayList<String> genePare(int n){
ArrayList<String> result = new ArrayList<String>();
if(n <= 0)
return result;
genePare(n, 0, 0, "", result);
return result;
}
private static void genePare(int n, int leftCount, int rightCount, String str, ArrayList<String> result){
//end
if(rightCount == n){
String temp = new String(str);
result.add(temp);
return;
}
//add left
if(leftCount < n){
genePare(n, leftCount+1, rightCount, str+"(", result);
}
//add right
if(rightCount < leftCount){
genePare(n, leftCount, rightCount+1, str+")", result);
}
}
public static void main(String[] args) {
int n = 3;
ArrayList<String> result = genePare(n);
for(String item : result){
System.out.println(item);
}
}
}