cangoal

//
public List<Interval> merge(List<Interval> intervals) {
        ArrayList<Interval> ret = new ArrayList<Interval>();
        if(intervals == null || intervals.size() ==0) return ret;
        Collections.sort(intervals, comparator);
        Interval newInterval = intervals.get(0);
        for(int i=1; i<intervals.size(); i++){
            Interval curInterval = intervals.get(i);
            if(curInterval.start > newInterval.end){
                ret.add(newInterval);

cangoal

// http://www.programcreek.com/2013/09/string-is-passed-by-reference-in-java/

public static void test (){
	ArrayList<StringBuilder> ret = new ArrayList<StringBuilder>();
	StringBuilder sb = new StringBuilder("abc");
	ret.add(sb);
	sb.append("d"); // sb = new StringBuilder("cba")
	System.out.println(ret.toString());
	
	ArrayList<String> lst = new ArrayList<String>();

cangoal

public List<Interval> insert(List<Interval> intervals, Interval newInterval) {
    ArrayList<Interval> ret = new ArrayList<Interval>();
    if(intervals == null || intervals.size() == 0){
        ret.add(newInterval);
        return ret;
    }
    for(int i=0; i<intervals.size(); i++){
        Interval curInterval = intervals.get(i);
        if(curInterval.end < newInterval.start){
            ret.add(curInterval);

cangoal

//
public int lengthOfLastWord(String s) {
        if(s==null || s.length()==0) return 0;
        int i=s.length()-1;
        for(; i>=0; i--){
            if(s.charAt(i) != ' ') break;
        }
        int j = i;
        for(; j>=0; j--){
            if(s.charAt(j) == ' ') break;

cangoal

// consider case k =0 seperately
public ListNode rotateRight(ListNode head, int k) {
        if(head == null) return head;
        int size = 1;
        ListNode cur = head;
        while(cur.next != null){
            cur = cur.next;
            size++;
        }
        k  = k % size;

cangoal

//
public int uniquePaths(int m, int n) {
        if(m<1 || n<1) return 0;
        if(m==1 || n==1) return 1;
        int[][] ret = new int[m][n];
        
        for(int i=0; i<m; i++){
            ret[i][0] = 1;
        }
        

cangoal

//
public int uniquePathsWithObstacles(int[][] obstacleGrid) {
         if(obstacleGrid == null || obstacleGrid.length == 0 || obstacleGrid[0].length == 0)
            return 0;
        int m = obstacleGrid.length, n = obstacleGrid[0].length;
        int[] res = new int[n];
        if(obstacleGrid[0][0] == 0) res[0] = 1;
            else res[0] = 0;
        for(int i=0;i<m;i++)
        {

cangoal

public String simplifyPath(String path) {
        if(path == null || path.length() == 0) return path;
        String[] arr = path.split("/");
        Stack<String> stack = new Stack<String>();
        for(int i = 0; i < arr.length; i++){
            if(arr[i].length() > 0){
                if(arr[i].equals("..")){
                    if(!stack.isEmpty()) stack.pop();
                } else if (arr[i].equals(".")){
                    continue;

cangoal

public ArrayList<ArrayList<Integer>> combine(int n, int k) {
        ArrayList<ArrayList<Integer>> ret = new ArrayList<ArrayList<Integer>>();
        if(n <= 0 || k <= 0 || n < k) return ret;
        helper(ret, n, k, 1, new ArrayList<Integer>());
        return ret; 
    }
    
    public void helper(ArrayList<ArrayList<Integer>> ret, int n, int k, int start , ArrayList<Integer> lst){
        if(lst.size() == k){
            ret.add(new ArrayList<Integer>(lst));

cangoal

//
public int search(int[] nums, int target) {
        if(nums == null || nums.length==0) return -1;
        int left = 0, right = nums.length-1;
        while(left <= right){
            int mid = (left + right) / 2;
            if(nums[mid] == target){
                return mid;
            }else if(nums[mid] >= nums[left]){
                if(target >= nums[left] && nums[mid] > target){