leetcodesolutions/code/968.binary-tree-cameras.java at main · Raghuram42/leetcodesolutions · GitHub

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
/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
class Solution {
    int res = 0;
    public int minCameraCover(TreeNode root) {
        if(root == null)
            return 0;
        if(root.left == null && root.right == null)
            return 1;
        return minCamera(root) == 0 ? res+1: res;
    }

    public int minCamera(TreeNode root){
        if(root == null)
            return 1;
        int dc1 = minCamera(root.left);
        int dc2 = minCamera(root.right);

        if(dc1 == 0 || dc2 == 0)
        {
            res++;
            return 2;
        }

        if(dc1 == 1 && dc2 == 1)
            return 0;

        return 1;

    }
}