FilesExpand file tree

 master

/

CombinationSum.java

Copy path

Blame

More file actions

Blame

More file actions

Latest commit

 

History

History

History

78 lines (53 loc) · 2.07 KB

 master

/

CombinationSum.java

Copy path

Top

File metadata and controls

• Code
• Blame

78 lines (53 loc) · 2.07 KB

Raw

Copy raw file

Download raw file

Open symbols panel

Edit and raw actions

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

47

48

49

50

51

52

53

54

55

56

57

58

59

60

61

62

63

64

65

66

67

68

69

70

71

72

73

74

75

76

77

78

package Algorithms;

import java.util.ArrayList;

import java.util.Arrays;

public class CombinationSum{

public ArrayList<ArrayList<Integer>> combine(int n, int k) {

ArrayList<ArrayList<Integer>> rst = new ArrayList<ArrayList<Integer>>();

help(n, 0, new ArrayList<Integer>(), rst, k);

return rst;

}

public void help(int n, int index, ArrayList<Integer> path, ArrayList<ArrayList<Integer>> rst, int k) {

if (path.size() == k) {

rst.add(new ArrayList<Integer>(path));

return;

}

for (int i = index; i < n; i++) {

path.add(i + 1);

help(n, i + 1, path, rst, k);

path.remove(path.size() - 1);

}

return;

}

public static void main(String[] args) {

CombinationSum cs = new CombinationSum();

int[] num = {1,2};

cs.combine(1, 1);

}

public ArrayList<ArrayList<Integer>> combinationSum(int[] candidates, int target) {

ArrayList<ArrayList<Integer>> rst = new ArrayList<ArrayList<Integer>> ();

Arrays.sort(candidates);

help(candidates, 0, new ArrayList<Integer>(), rst, target);

System.out.printf(rst.toString());

return rst;

}

public void help(int[] cand, int index, ArrayList<Integer> path, ArrayList<ArrayList<Integer>> rst, int target) {

if (target == 0) {

// add the current set into the result.

rst.add(new ArrayList<Integer>(path));

return;

}

int pre = -1;

for (int i = index; i < cand.length; i++) {

if (cand[i] > target) {

// because the sequence is ascending, so we don't need to go on.

break;

}

if (cand[i] == pre)

path.add(cand[i]);

help(cand, index, path, rst, target - cand[i]);

path.remove(path.size() - 1);

}

return;

}

}