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Sum Root to Leaf Numbers
1
sumNumbers(Node(1))
Simple (sum=25)
Medium (sum=1026)
Two leaves (sum=110)
Custom
tree
=
[1, 2, 3]
1
2
3
numbers
num
0
sum
0
each root-to-leaf path spells a number
1
2
3
numbers
num
0
sum
0
each root-to-leaf path spells a number
1
2
3
numbers
num
0
sum
0
dfs(root,
0
)
1
2
3
1
numbers
num
1
sum
0
num =
0
* 10 +
1
=
1
1
2
3
1
numbers
num
1
sum
0
recurse left, carrying
1
1
2
3
1
12
numbers
num
12
sum
0
num =
1
* 10 +
2
=
12
1
2
3
1
12
numbers
12
num
1
sum
12
recurse right, carrying
1
1
2
3
1
12
13
numbers
12
num
13
sum
12
num =
1
* 10 +
3
=
13
1
2
3
1
12
13
numbers
12
+
13
num
13
sum
25
leaf: sum =
12
+
13
=
25
1
2
3
1
12
13
numbers
12
+
13
num
1
sum
25
return
12
+
13
=
25
1
2
3
1
12
13
numbers
12
+
13
sum
25
return 25
Step:
Start: every root-to-leaf path spells out a number, sum them all
0 / 10
Simple (sum=25)
Medium (sum=1026)
Two leaves (sum=110)
Custom
tree
=
[1, 2, 3]
0 / 10
Step:
Start: every root-to-leaf path spells out a number, sum them all
1
sumNumbers(Node(1))
