Contains Duplicate III-优快云博客

本文链接：https://blog.youkuaiyun.com/yeshiwu/article/details/52767983

本文介绍了一种算法问题的解决方法，即在给定整数数组中查找是否存在两个不同的索引 i 和 j，使得 nums[i] 和 nums[j] 的差的绝对值不超过 t，且 i 和 j 的差不超过 k。提供了两种解决方案：一种使用 TreeSet 实现滑动窗口；另一种使用自定义二叉搜索树。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

题目描述：

Given an array of integers, find out whether there are two distinct indices i and j in the array such that the difference between nums[i] and nums[j] is at most t and the difference between i and j is at most k.

这个题和前面的2个没有什么关系。

滑动窗口+treeset做法：

public boolean containsNearbyAlmostDuplicate(int[] nums, int k, int t) {
    if (nums == null || nums.length == 0 || k <= 0) {
        return false;
    }

    final TreeSet<Integer> values = new TreeSet<>();
    for (int ind = 0; ind < nums.length; ind++) {
        final Integer floor = values.floor(nums[ind] + t);
        final Integer ceil = values.ceiling(nums[ind] - t);
        if ((floor != null && floor >= nums[ind])
                || (ceil != null && ceil <= nums[ind])) {
            return true;
        }
        values.add(nums[ind]);
        if (ind >= k) {
            values.remove(nums[ind - k]);
        }
    }

    return false;
}

二叉搜索树做法，其实和上面的思想一样，但是这个写起来太麻烦~~~

public class Solution {
    class TreeNode{
		long val;
		TreeNode left;
		TreeNode right;
		public TreeNode(long x) {
			val = x;
		}
	}
	private TreeNode add(TreeNode root, TreeNode nNode) {
	    if(root == null) {
	        return nNode;
	    }
	    else if(root.val < nNode.val) {
	        root.right = add(root.right, nNode);
	        return root;
	    }
	    else {
	        root.left = add(root.left, nNode);
	        return root;
	    }
	}

	private TreeNode delete(TreeNode root, TreeNode dNode) {
	    if(root == null) {
	        return null;
	    }
	    else if(root.val < dNode.val) {
	        root.right = delete(root.right, dNode);
	        return root;
	    }
	    else if(root.val > dNode.val) {
	        root.left = delete(root.left, dNode);
	        return root;
	    }
	    else if(root == dNode) {
	         if(dNode.left == null && dNode.right == null) return null;
	         else if(dNode.left != null && dNode.right == null) return dNode.left;
	         else if(dNode.right != null && dNode.left == null) return dNode.right;
	         else {
	             TreeNode p = dNode.right;
	             while(p.left != null) p = p.left;
	             dNode.right = delete(dNode.right, p);
	             p.left = dNode.left;
	             p.right = dNode.right;
	             return p;
	         }
	    }
	    else {
	        return root;
	    }
	}

	private boolean search(TreeNode root, long val, int t) {
	    if(root == null) {
	        return false;
	    }
	    else if(Math.abs((root.val - val)) <= t) {
	        return true;
	    }
	    else if((root.val - val) > t) {
	        return search(root.left, val, t);
	    }
	    else {
	        return search(root.right, val, t);
	    }
	}

	public boolean containsNearbyAlmostDuplicate(int[] nums, int k, int t) {
	    if(k < 1 || t < 0 || nums.length <= 1) {
	        return false;
	    }
	    int len = nums.length;
	    TreeNode[] map = new TreeNode[len];
	    map[0] = new TreeNode((long)nums[0]);
	    TreeNode root = null;
	    root = add(root, map[0]);
	    for(int i = 1; i < len; i++) {
	        if(search(root, (long)nums[i], t)) {
	            return true;
	        }
	        map[i] = new TreeNode((long)nums[i]);
	        if(i - k >= 0) {
	            root = delete(root, map[i-k]);
	        }
	        root = add(root, map[i]);
	    }
	    return false;
	}
}

下面这个方法也很巧妙：！！！将value和index存储起来，然后排序

class Pair {
    int val;
    int index;
    Pair(int v, int i) {
        this.val = v;
        this.index = i;
    }
	@Override
	public String toString() {
		return "Pair [val=" + val + ", index=" + index + "]";
	}
    
}

public boolean containsNearbyAlmostDuplicate(int[] nums, int k, int t) {
    if (nums == null || nums.length < 2 || t < 0 || k < 1) {
        return false;
    }
    int len = nums.length;
    Pair[] pair = new Pair[len];
    for(int i = 0; i < len; i++) {
        pair[i] = new Pair(nums[i], i);
    }
    
    Arrays.sort(pair, new Comparator<Pair> () {
      public int compare(Pair p1, Pair p2) {
          return p1.val - p2.val;
      } 
    });
    
    for (int i = 0; i < pair.length; i++) {
		System.out.println(pair[i]);
	}
    
    for(int i = 0; i < len; i++) {
        for(int j = i + 1; j < len && Math.abs((long)pair[j].val - (long)pair[i].val) <= (long)t; j++){
            int indexDiff = Math.abs(pair[i].index - pair[j].index);
            if (indexDiff <= k) {
                return true;
            }
        }
    }
    return false;
}