1 public class SortNumbersWithTwoStacks {
2 Deque<Integer> stack1 = new LinkedList<>();
3 Deque<Integer> stack2 = new LinkedList<>();
4
5
6 public SortNumbersWithTwoStacks() {
7 stack1.push(1);
8 stack1.push(2);
9 stack1.push(4);
10 stack1.push(1);
11 stack1.push(2);
12 stack1.push(1);
13 stack1.push(3);
14 stack1.push(2);
15 }
16 /*
17 * stack1: sorted|unsorted
18 * stack2: buffer place
19 * globalMin: current iteration smallest value
20 * counter: how many times in the current iteration the globalMin shows
21 * */
22 private void sort(){
23 int globalMin = Integer.MAX_VALUE ;
24 int itemsToSort = stack1.size() ;
25 //counter for # of same items as globalMin
26 int counter = 0 ;
27 for (int i = 0; i < itemsToSort ;) {
28 //for every sort, globalMin = top item of stack1; also reset the counter = 1
29 counter = 1 ;
30 globalMin = stack1.pop() ;
31 while (!stack1.isEmpty()){
32 int value = stack1.pop() ;
33 if (value<globalMin){
34 for (int j = counter; j >0 ; j--) {
35 stack2.push(globalMin);
36 }
37 counter = 1 ;
38 globalMin = value ;
39 } else if(value == globalMin){
40 counter++ ;
41 } else{
42 stack2.push(value);
43 }
44 }
45 //now add back globalMin
46 for (int j = counter; j >0 ; j--) {
47 stack1.push(globalMin);
48 /*
49 this is to make sure no dupl add. make sure the outside loop doesnt have i++
50 otherwise will jump over one
51 * */
52 i++;
53 }
54 //and then add back stack2
55 while (!stack2.isEmpty()){
56 stack1.push(stack2.pop());
57 }
58 }
59 }
60
61 public static void main(String[] args) {
62 SortNumbersWithTwoStacks sort = new SortNumbersWithTwoStacks();
63 sort.sort();
64 while (!sort.stack1.isEmpty()) {
65 System.out.println(sort.stack1.pop());
66 }
67 }
68 }
TEST:
