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@@ -0,0 +1,47 @@
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+/**
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+ * Definition for singly-linked list.
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+ * type ListNode struct {
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+ * Val int
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+ * Next *ListNode
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+ * }
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+ */
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+func addTwoNumbers(l1 *ListNode, l2 *ListNode) *ListNode {
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+ if l1 == nil {
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+ return l2
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+ } else if l2 == nil {
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+ return l1
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+ }
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+ m, n := 0, 0
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+ for cur := l1; cur != nil; cur, m = cur.Next, m+1 {
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+ }
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+ for cur := l2; cur != nil; cur, n = cur.Next, n+1 {
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+ }
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+ var li *ListNode
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+ var rem int
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+ if m < n {
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+ li, rem = addRecurse(l2, l1, n, m, 0)
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+ } else {
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+ li, rem = addRecurse(l1, l2, m, n, 0)
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+ }
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+ if rem != 0 {
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+ li = &ListNode{rem, li}
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+ }
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+ return li
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+}
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+
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+func addRecurse(l1, l2 *ListNode, m, n, i int) (*ListNode, int) { // n <= m
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+ if i == m {
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+ return nil, 0
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+ }
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+ a, b := l1.Val, 0
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+ next1, next2 := l1.Next, l2
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+ if m-n <= i {
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+ b = l2.Val
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+ next2 = l2.Next
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+ }
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+ li, rem := addRecurse(next1, next2, m, n, i+1)
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+ c := a + b + rem
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+ c, rem = c%10, c/10
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+ li = &ListNode{c, li}
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+ return li, rem
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+}
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