LintCode:线段树的查询

LintCode:线段树的查询

"""
Definition of SegmentTreeNode:
class SegmentTreeNode:
    def __init__(self, start, end, max):
        self.start, self.end, self.max = start, end, max
        self.left, self.right = None, None
"""

class Solution: 
    # @param root, start, end: The root of segment tree and 
    #                          an segment / interval
    # @return: The maximum number in the interval [start, end]
    def query(self, root, start, end):
        # write your code here
        if root == None:
            return 0
        if root.start > end or root.end < start or start > end:
            return 0
        if root.start >= start and root.end <= end:
            return root.max

        mid = root.start + (root.end - root.start) / 2
        left_max = self.query(root.left, start, min(mid, end))
        right_max = self.query(root.right, max(start, mid), end)
        return max(left_max, right_max)

Java

/**
 * Definition of SegmentTreeNode:
 * public class SegmentTreeNode {
 *     public int start, end, max;
 *     public SegmentTreeNode 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 class Solution {
    /**
     *@param root, start, end: The root of segment tree and 
     *                         an segment / interval
     *@return: The maximum number in the interval [start, end]
     */
    public int query(SegmentTreeNode root, int start, int end) {
        // write your code here
        if(root == null){
            return 0;
        }
        if(root.start > end || root.end < start || start > end){
            return 0;
        }
        if(root.start >= start && root.end <= end){
            return root.max;
        }

        int mid = root.start + (root.end - root.start)/2;
        int leftMax = query(root.left, start, Math.min(mid, end));
        int rightMax = query(root.right, Math.max(start, mid), end);

        return Math.max(leftMax, rightMax);
    }
}