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GenerateParenthesis.java
59 lines (56 loc) · 2.05 KB
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GenerateParenthesis.java
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import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public class GenerateParenthesis {
public static List<String> generateParenthesis(int n) {
List<String> result = new ArrayList<String>();
char[] str = new char[n * 2];
generateParenthesis(n, n , str, 0, result);
return result;
}
private static void generateParenthesis(int left, int right, char[] str,
int length, List<String> result) {
if (length == str.length) {
result.add(String.valueOf(str));
} else {
if (left == right) {
str[length] = '(';
generateParenthesis(left - 1, right, str, length + 1, result);
} else if (left < right) {
if (left > 0) {
str[length] = '(';
generateParenthesis(left - 1, right, str, length + 1, result);
}
str[length] = ')';
generateParenthesis(left, right - 1, str, length + 1, result);
}
}
}
// public static List<String> generateParenthesis(int n) {
// List<String> result = new ArrayList<String>();
// generateParenthesis(n, n , n, "", result);
// return result;
// }
// private static void generateParenthesis(int left, int right, int n,
// String s, List<String> result) {
//
// if (s.length() == n * 2) {
// result.add(s);
// } else {
// if (left == right) {
// generateParenthesis(left - 1, right, n , s + "(", result);
// } else if (left < right) {
// if (left > 0) {
// generateParenthesis(left - 1, right, n , s + "(", result);
// }
// generateParenthesis(left, right - 1, n, s + ")", result);
// }
// }
// }
public static void main(String[] args) {
List<String> result = generateParenthesis(3);
for (String s: result) {
System.out.println(s);
}
}
}