|
| 1 | +/** |
| 2 | + * Definition for singly-linked list. |
| 3 | + * function ListNode(val, next) { |
| 4 | + * this.val = (val===undefined ? 0 : val) |
| 5 | + * this.next = (next===undefined ? null : next) |
| 6 | + * } |
| 7 | + */ |
| 8 | +/** |
| 9 | + *@param {ListNode} head |
| 10 | + *@param {number} left |
| 11 | + *@param {number} right |
| 12 | + *@return {ListNode} |
| 13 | + */ |
| 14 | +varreverseBetween=function(head,left,right){ |
| 15 | +if(!head||!head.next||left===right){ |
| 16 | +returnhead; |
| 17 | +} |
| 18 | +letidx=1; |
| 19 | +letprevLower=null; |
| 20 | +letcurLower=head; |
| 21 | +while(curLower&&idx<left){ |
| 22 | +prevLower=curLower; |
| 23 | +curLower=curLower.next; |
| 24 | +idx++; |
| 25 | +} |
| 26 | +letstoredPrevLower=prevLower; |
| 27 | +letstoredCurLower=curLower; |
| 28 | +letprevPtr=null; |
| 29 | +lettmpPtr=null; |
| 30 | +while(curLower&&idx<=right){ |
| 31 | +tmpPtr=curLower.next; |
| 32 | +curLower.next=prevPtr; |
| 33 | +prevPtr=curLower; |
| 34 | +curLower=tmpPtr; |
| 35 | +idx++; |
| 36 | +} |
| 37 | +if(storedPrevLower){ |
| 38 | +storedPrevLower.next=prevPtr; |
| 39 | +} |
| 40 | +storedCurLower.next=curLower; |
| 41 | +returnstoredPrevLower ?head :prevPtr; |
| 42 | +}; |