feat: add solutions to lc problem: No.0295 (doocs#3166)

Co-authored-by: Libin YANG <contact@yanglibin.info>

Author: rain84

solution/0200-0299/0295.Find Median from Data Stream/README.md

@@ -1,34 +1,31 @@
 class MedianFinder {
 public:
-    /** initialize your data structure here. */
     MedianFinder() {
     }
 
     void addNum(int num) {
-        q1.push(num);
-        q2.push(q1.top());
-        q1.pop();
-        if (q2.size() - q1.size() > 1) {
-            q1.push(q2.top());
-            q2.pop();
+        maxQ.push(num);
+        minQ.push(maxQ.top());
+        maxQ.pop();
+
+        if (minQ.size() > maxQ.size() + 1) {
+            maxQ.push(minQ.top());
+            minQ.pop();
         }
     }
 
     double findMedian() {
-        if (q2.size() > q1.size()) {
-            return q2.top();
-        }
-        return (double) (q1.top() + q2.top()) / 2;
+        return minQ.size() == maxQ.size() ? (minQ.top() + maxQ.top()) / 2.0 : minQ.top();
     }
 
 private:
-    priority_queue<int, vector<int>, greater<int>> q1;
-    priority_queue<int> q2;
+    priority_queue<int> maxQ;
+    priority_queue<int, vector<int>, greater<int>> minQ;
 };
 
 /**
  * Your MedianFinder object will be instantiated and called as such:
  * MedianFinder* obj = new MedianFinder();
  * obj->addNum(num);
  * double param_2 = obj->findMedian();
- */
+ */

solution/0200-0299/0295.Find Median from Data Stream/README_EN.md

@@ -1,50 +1,21 @@
 public class MedianFinder {
-    private List<int> nums;
-    private int curIndex;
+    private PriorityQueue<int, int> minQ = new PriorityQueue<int, int>();
+    private PriorityQueue<int, int> maxQ = new PriorityQueue<int, int>(Comparer<int>.Create((a, b) => b.CompareTo(a)));
 
-    /** initialize your data structure here. */
     public MedianFinder() {
-        nums = new List<int>();
-    }
 
-    private int FindIndex(int val) {
-        int left = 0;
-        int right = nums.Count - 1;
-        while (left <= right) {
-            int mid = left + (right - left) / 2;
-            if (val > nums[mid]) {
-                left = mid + 1;
-            } else {
-                right = mid - 1;
-            }
-        }
-        return left;
     }
 
     public void AddNum(int num) {
-        if (nums.Count == 0) {
-            nums.Add(num);
-            curIndex = 0;
-        } else {
-            curIndex = FindIndex(num);
-            if (curIndex == nums.Count) {
-                nums.Add(num);
-            } else {
-                nums.Insert(curIndex, num);
-            }
+        maxQ.Enqueue(num, num);
+        minQ.Enqueue(maxQ.Peek(), maxQ.Dequeue());
+        if (minQ.Count > maxQ.Count + 1) {
+            maxQ.Enqueue(minQ.Peek(), minQ.Dequeue());
         }
     }
 
     public double FindMedian() {
-        if (nums.Count % 2 == 1) {
-            return (double)nums[nums.Count / 2];
-        } else {
-            if (nums.Count == 0) {
-                return 0;
-            } else {
-                return (double) (nums[nums.Count / 2 - 1] + nums[nums.Count / 2]) / 2;
-            }
-        }
+        return minQ.Count == maxQ.Count ? (minQ.Peek() + maxQ.Peek()) / 2.0 : minQ.Peek();
     }
 }
 

solution/0200-0299/0295.Find Median from Data Stream/Solution.cpp

@@ -1,35 +1,29 @@
 type MedianFinder struct {
-	q1 hp
-	q2 hp
+	minq hp
+	maxq hp
 }
 
-/** initialize your data structure here. */
 func Constructor() MedianFinder {
 	return MedianFinder{hp{}, hp{}}
 }
 
 func (this *MedianFinder) AddNum(num int) {
-	heap.Push(&this.q1, num)
-	heap.Push(&this.q2, -heap.Pop(&this.q1).(int))
-	if this.q2.Len()-this.q1.Len() > 1 {
-		heap.Push(&this.q1, -heap.Pop(&this.q2).(int))
+	minq, maxq := &this.minq, &this.maxq
+	heap.Push(maxq, -num)
+	heap.Push(minq, -heap.Pop(maxq).(int))
+	if minq.Len()-maxq.Len() > 1 {
+		heap.Push(maxq, -heap.Pop(minq).(int))
 	}
 }
 
 func (this *MedianFinder) FindMedian() float64 {
-	if this.q2.Len() > this.q1.Len() {
-		return -float64(this.q2.IntSlice[0])
+	minq, maxq := this.minq, this.maxq
+	if minq.Len() == maxq.Len() {
+		return float64(minq.IntSlice[0]-maxq.IntSlice[0]) / 2
 	}
-	return float64(this.q1.IntSlice[0]-this.q2.IntSlice[0]) / 2.0
+	return float64(minq.IntSlice[0])
 }
 
-/**
- * Your MedianFinder object will be instantiated and called as such:
- * obj := Constructor();
- * obj.AddNum(num);
- * param_2 := obj.FindMedian();
- */
-
 type hp struct{ sort.IntSlice }
 
 func (h hp) Less(i, j int) bool { return h.IntSlice[i] < h.IntSlice[j] }
@@ -39,4 +33,11 @@ func (h *hp) Pop() any {
 	v := a[len(a)-1]
 	h.IntSlice = a[:len(a)-1]
 	return v
-}
+}
+
+/**
+ * Your MedianFinder object will be instantiated and called as such:
+ * obj := Constructor();
+ * obj.AddNum(num);
+ * param_2 := obj.FindMedian();
+ */

solution/0200-0299/0295.Find Median from Data Stream/Solution.cs

@@ -1,24 +1,20 @@
 class MedianFinder {
-    private PriorityQueue<Integer> q1 = new PriorityQueue<>();
-    private PriorityQueue<Integer> q2 = new PriorityQueue<>(Collections.reverseOrder());
+    private PriorityQueue<Integer> minQ = new PriorityQueue<>();
+    private PriorityQueue<Integer> maxQ = new PriorityQueue<>(Collections.reverseOrder());
 
-    /** initialize your data structure here. */
     public MedianFinder() {
     }
 
     public void addNum(int num) {
-        q1.offer(num);
-        q2.offer(q1.poll());
-        if (q2.size() - q1.size() > 1) {
-            q1.offer(q2.poll());
+        maxQ.offer(num);
+        minQ.offer(maxQ.poll());
+        if (minQ.size() - maxQ.size() > 1) {
+            maxQ.offer(minQ.poll());
         }
     }
 
     public double findMedian() {
-        if (q2.size() > q1.size()) {
-            return q2.peek();
-        }
-        return (q1.peek() + q2.peek()) * 1.0 / 2;
+        return minQ.size() == maxQ.size() ? (minQ.peek() + maxQ.peek()) / 2.0 : minQ.peek();
     }
 }
 
@@ -27,4 +23,4 @@ public double findMedian() {
  * MedianFinder obj = new MedianFinder();
  * obj.addNum(num);
  * double param_2 = obj.findMedian();
- */
+ */

solution/0200-0299/0295.Find Median from Data Stream/Solution.go

@@ -1,32 +1,33 @@
-/**
- * initialize your data structure here.
- */
 var MedianFinder = function () {
-    this.val = [];
+    this.minQ = new MinPriorityQueue();
+    this.maxQ = new MaxPriorityQueue();
 };
 
 /**
  * @param {number} num
  * @return {void}
  */
 MedianFinder.prototype.addNum = function (num) {
-    let left = 0;
-    let right = this.val.length;
-    while (left < right) {
-        let mid = left + ~~((right - left) / 2);
-        if (num > this.val[mid]) {
-            left = mid + 1;
-        } else {
-            right = mid;
-        }
+    this.maxQ.enqueue(num);
+    this.minQ.enqueue(this.maxQ.dequeue().element);
+    if (this.minQ.size() - this.maxQ.size() > 1) {
+        this.maxQ.enqueue(this.minQ.dequeue().element);
     }
-    this.val.splice(left, 0, num);
 };
 
 /**
  * @return {number}
  */
 MedianFinder.prototype.findMedian = function () {
-    let mid = ~~(this.val.length / 2);
-    return this.val.length % 2 ? this.val[mid] : (this.val[mid - 1] + this.val[mid]) / 2;
+    if (this.minQ.size() === this.maxQ.size()) {
+        return (this.minQ.front().element + this.maxQ.front().element) / 2;
+    }
+    return this.minQ.front().element;
 };
+
+/**
+ * Your MedianFinder object will be instantiated and called as such:
+ * var obj = new MedianFinder()
+ * obj.addNum(num)
+ * var param_2 = obj.findMedian()
+ */

solution/0200-0299/0295.Find Median from Data Stream/Solution.java

@@ -1,21 +1,18 @@
 class MedianFinder:
+
     def __init__(self):
-        """
-        initialize your data structure here.
-        """
-        self.h1 = []
-        self.h2 = []
+        self.minq = []
+        self.maxq = []
 
     def addNum(self, num: int) -> None:
-        heappush(self.h1, num)
-        heappush(self.h2, -heappop(self.h1))
-        if len(self.h2) - len(self.h1) > 1:
-            heappush(self.h1, -heappop(self.h2))
+        heappush(self.minq, -heappushpop(self.maxq, -num))
+        if len(self.minq) - len(self.maxq) > 1:
+            heappush(self.maxq, -heappop(self.minq))
 
     def findMedian(self) -> float:
-        if len(self.h2) > len(self.h1):
-            return -self.h2[0]
-        return (self.h1[0] - self.h2[0]) / 2
+        if len(self.minq) == len(self.maxq):
+            return (self.minq[0] - self.maxq[0]) / 2
+        return self.minq[0]
 
 
 # Your MedianFinder object will be instantiated and called as such:

solution/0200-0299/0295.Find Median from Data Stream/Solution.js

@@ -1,36 +1,35 @@
+use std::cmp::Reverse;
+use std::collections::BinaryHeap;
+
 struct MedianFinder {
-    nums: Vec<i32>,
+    minQ: BinaryHeap<Reverse<i32>>,
+    maxQ: BinaryHeap<i32>,
 }
 
-/**
- * `&self` means the method takes an immutable reference.
- * If you need a mutable reference, change it to `&mut self` instead.
- */
 impl MedianFinder {
-    /** initialize your data structure here. */
     fn new() -> Self {
-        Self { nums: Vec::new() }
+        MedianFinder {
+            minQ: BinaryHeap::new(),
+            maxQ: BinaryHeap::new(),
+        }
     }
 
     fn add_num(&mut self, num: i32) {
-        let mut l = 0;
-        let mut r = self.nums.len();
-        while l < r {
-            let mid = (l + r) >> 1;
-            if self.nums[mid] < num {
-                l = mid + 1;
-            } else {
-                r = mid;
-            }
+        self.maxQ.push(num);
+        self.minQ.push(Reverse(self.maxQ.pop().unwrap()));
+
+        if self.minQ.len() > self.maxQ.len() + 1 {
+            self.maxQ.push(self.minQ.pop().unwrap().0);
         }
-        self.nums.insert(l, num);
     }
 
     fn find_median(&self) -> f64 {
-        let n = self.nums.len();
-        if (n & 1) == 1 {
-            return f64::from(self.nums[n >> 1]);
+        if self.minQ.len() == self.maxQ.len() {
+            let min_top = self.minQ.peek().unwrap().0;
+            let max_top = *self.maxQ.peek().unwrap();
+            (min_top + max_top) as f64 / 2.0
+        } else {
+            self.minQ.peek().unwrap().0 as f64
         }
-        f64::from(self.nums[n >> 1] + self.nums[(n >> 1) - 1]) / 2.0
     }
 }