Lintcode-medium-segment Tree Modify

For a Maximum Segment Tree , which each node have an extra value to max store the maximum value in this node ' s interval.

Implement a modify function with three parameter root , and to change the index value node's value with [start, end] = [Index, index] To the new given value. Make sure the Every node in segment tree still have the Max attribute with the correct value.

Example

For segment tree:

                      [1, 4, max=3]                    /                        [1, 2, max=2]                [3, 4, max=3]       /              \             /             [1, 1, max=2], [2, 2, max=1], [3, 3, max=0], [4, 4, max=3]

If call modify(root, 2, 4) , we can get:

                      [1, 4, max=4]                    /                        [1, 2, max=4]                [3, 4, max=3]       /              \             /             [1, 1, max=2], [2, 2, max=4], [3, 3, max=0], [4, 4, max=3]

or call modify(root, 4, 0) , we can get:

                      [1, 4, max=2]                    /                        [1, 2, max=2]                [3, 4, max=0]       /              \             /             [1, 1, max=2], [2, 2, max=1], [3, 3, max=0], [4, 4, max=0]

Challenge

Do it O(h) in time, and H is the height of the segment tree.

/*** Definition of Segmenttreenode: * public class Segmenttreenode {* Public int start, end, Max; * Public Segm Enttreenode left, right;         * Public Segmenttreenode (int start, int end, int max) {* This.start = start; * This.end = end; * This.max = max * This.left = This.right = null; *     } * } */ Public classSolution {/**     *@paramroot, index, value:the root of Segment tree and *@ Change the node's value with [Index, index] to the new given Value *@return: void*/     Public voidModify (Segmenttreenode root,intIndexintvalue) {        //Write your code here        if(Index > Root.end | | | Index <Root.start)return; if(Root.start = = Root.end && Root.start = =index) {Root.max=value; return; }                intMID = Root.start + (Root.end-root.start)/2; if(Index <=mid)        {Modify (root.left, index, value); }        Else{Modify (root.right, index, value); } Root.max=Math.max (Root.left.max, Root.right.max); return; }}

Lintcode-medium-segment Tree Modify