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480.java
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480.java
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__________________________________________________________________________________________________
sample 7 ms submission
/*
* @lc app=leetcode id=480 lang=java
* 2 treemap 52%(32ms)
*
* [480] Sliding Window Median
*/
class Solution {
//*
class Node {
int val;
int count;
int leftCount;
Node left;
Node right;
public Node(int v) {
val = v;
}
}
public void add(Node n, int x) {
if (x == n.val) {
++n.count;
} else if (x < n.val) {
n.leftCount++;
if (n.left == null) n.left = new Node(x);
add(n.left, x);
} else {
if (n.right == null) n.right = new Node(x);
add(n.right, x);
}
}
public void remove(Node n, int x) {
if (x == n.val) {
--n.count;
} else if (x < n.val) {
--n.leftCount;
remove(n.left, x);
} else {
remove(n.right, x);
}
}
public int getValue(Node n, int i) {
return i < n.leftCount ? getValue(n.left, i)
: i >= n.leftCount + n.count ? getValue(n.right, i-n.leftCount-n.count)
: n.val;
}
public double[] medianSlidingWindow(int[] nums, int k) {
double[] res = new double[nums.length - k + 1];
Node root = new Node(0);
for (int i = 0; i < nums.length; ++i) {
if (i >= k) {
remove(root, nums[i-k]);
}
add(root, nums[i]);
if (i >= k-1) {
res[i-k+1] = k % 2 == 0
? ((double)getValue(root, k/2) + getValue(root, (k-1)/2)) / 2
: (double)getValue(root, k/2);
}
}
return res;
}
}
__________________________________________________________________________________________________
sample 38732 kb submission
class Solution {
// can use 2 treeset, and store the index to avoid duplicate values, (multiset)
public double[] medianSlidingWindow(int[] nums, int k) {
Comparator<Integer> comparator = (a, b) -> nums[a] != nums[b] ? Integer.compare(nums[a], nums[b]) : a - b;
TreeSet<Integer> minSet = new TreeSet<>(comparator);
TreeSet<Integer> maxSet = new TreeSet<>(comparator.reversed());
int n = nums.length - k + 1;
if (n <= 0) return new double[0];
double[] ret = new double[n];
for (int i=0; i<k-1; i++) {
maxSet.add(i);
}
balance(maxSet, minSet);
for (int i=k-1, r=0; i<nums.length; i++, r++) {
minSet.add(i);
maxSet.add(minSet.pollFirst());
balance(maxSet, minSet);
ret[r] = getMedian(maxSet, minSet, nums);
if (!maxSet.remove(i-k+1)) {
minSet.remove(i-k+1);
}
}
return ret;
}
private double getMedian(TreeSet<Integer> maxSet, TreeSet<Integer> minSet, int[] nums) {
if (maxSet.isEmpty() && minSet.isEmpty()) return 0;
if (maxSet.size() == minSet.size()) {
return ((double)nums[maxSet.first()] + nums[minSet.first()])/2;
} else {
return (double) nums[minSet.first()];
}
}
private void balance(TreeSet<Integer> maxSet, TreeSet<Integer> minSet) {
while (maxSet.size() > minSet.size()) {
minSet.add(maxSet.pollFirst());
}
}
}
__________________________________________________________________________________________________