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LC#160 added optimal solution to find intersection of two linked listO(n+m) time, O(1) space

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Original file line number	Diff line number	Diff line change
`@@ -39,4 +39,39 @@ public ListNode getIntersectionNode(ListNode headA, ListNode headB) {`
`39`	`39`
`40`	`40`	`return null;`
`41`	`41`	`}`
	`42`	`+`
	`43`	`+ public ListNode getIntersectionNode2(ListNode headA, ListNode headB) {`
	`44`	`+ if (headA == null \|\| headB == null)`
	`45`	`+ return null;`
	`46`	`+`
	`47`	`+ int lenA = getLengthOfList(headA), lenB = getLengthOfList(headB);`
	`48`	`+`
	`49`	`+ int diff = Math.abs(lenA - lenB);`
	`50`	`+`
	`51`	`+ while (lenA > lenB) {`
	`52`	`+ headA = headA.next;`
	`53`	`+ lenA--;`
	`54`	`+ }`
	`55`	`+`
	`56`	`+ while (lenB > lenA) {`
	`57`	`+ headB = headB.next;`
	`58`	`+ lenB--;`
	`59`	`+ }`
	`60`	`+`
	`61`	`+ while (headA != headB) {`
	`62`	`+ headA = headA.next;`
	`63`	`+ headB = headB.next;`
	`64`	`+ }`
	`65`	`+`
	`66`	`+ return headA;`
	`67`	`+ }`
	`68`	`+`
	`69`	`+ private int getLengthOfList(ListNode head) {`
	`70`	`+ int len = 0;`
	`71`	`+ while (head != null) {`
	`72`	`+ len++;`
	`73`	`+ head = head.next;`
	`74`	`+ }`
	`75`	`+ return len;`
	`76`	`+ }`
`42`	`77`	`}`

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