✨ Add solution and testcases to problem 295

Author: Cori1109

leetcode/201-300/0295.Find-Median-from-Data-Stream/README.md

@@ -1,15 +1,27 @@
 # [295.Find Median from Data Stream][title]
 
-> [!WARNING|style:flat]
-> This question is temporarily unanswered if you have good ideas. Welcome to [Create Pull Request PR](https://github.com/kylesliu/awesome-golang-algorithm)
-
 ## Description
 
+The median is the middle value in an ordered integer list. If the size of the list is even, there is no middle value and the median is the mean of the two middle values.
+
+    For example, for arr = [2,3,4], the median is 3.
+    For example, for arr = [2,3], the median is (2 + 3) / 2 = 2.5.
+
+Implement the MedianFinder class:
+
+    MedianFinder() initializes the MedianFinder object.
+    void addNum(int num) adds the integer num from the data stream to the data structure.
+    double findMedian() returns the median of all elements so far. Answers within 10-5 of the actual answer will be accepted.
+
+
 **Example 1:**
 
 ```
-Input: a = "11", b = "1"
-Output: "100"
+Input
+["MedianFinder", "addNum", "addNum", "findMedian", "addNum", "findMedian"]
+[[], [1], [2], [], [3], []]
+Output
+[null, null, null, 1.5, null, 2.0]
 ```
 
 ## 题意

leetcode/201-300/0295.Find-Median-from-Data-Stream/Solution.go

@@ -1,5 +1,47 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+import "container/heap"
+
+type IntHeap []int
+
+func (ih IntHeap) Len() int { return len(ih) }
+func (ih IntHeap) Less(i, j int) bool { return ih[i] < ih[j] }
+func (ih IntHeap) Swap(i, j int) { ih[i], ih[j] = ih[j], ih[i] }
+func (ih *IntHeap) Push(num interface{}) {
+	*ih = append(*ih, num.(int))
+}
+func (ih *IntHeap) Pop() interface{} {
+	old := *ih
+	n := ih.Len()
+	num := old[n - 1]
+	*ih = old[: n - 1]
+	return num
+}
+
+type MedianFinder struct {
+	Small IntHeap
+	Large IntHeap
 }
+
+func Constructor() MedianFinder {
+	return MedianFinder{[]int{}, []int{}}
+}
+
+func (mf *MedianFinder) AddNum(num int)  {
+    if mf.Small.Len() == mf.Large.Len() {
+        heap.Push(&mf.Large, -num)
+        val := heap.Pop(&mf.Large)
+        heap.Push(&mf.Small, -(val.(int)))
+    } else {
+        heap.Push(&mf.Small, num)
+        val := heap.Pop(&mf.Small)
+        heap.Push(&mf.Large, -(val.(int)))
+    }
+}
+
+func (mf *MedianFinder) FindMedian() float64 {
+    if mf.Small.Len() == mf.Large.Len() {
+        return float64(mf.Small[0] - mf.Large[0]) / 2
+    }
+    return float64(mf.Small[0])
+}

leetcode/201-300/0295.Find-Median-from-Data-Stream/Solution_test.go

@@ -2,31 +2,52 @@ package Solution
 
 import (
 	"reflect"
-	"strconv"
 	"testing"
 )
 
 func TestSolution(t *testing.T) {
 	//	测试用例
-	cases := []struct {
-		name   string
-		inputs bool
-		expect bool
-	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+	var medianFinder MedianFinder
+	var median float64
+
+	// Test Case 1
+	medianFinder = Constructor()
+	medianFinder.AddNum(1)
+	medianFinder.AddNum(2)
+	median = medianFinder.FindMedian()
+	if !reflect.DeepEqual(median, 1.5) {
+		t.Fatalf("expected: %v, but got: %v", 1.5, median)
+	}
+	medianFinder.AddNum(3)
+	median = medianFinder.FindMedian()
+	if !reflect.DeepEqual(median, 2.0) {
+		t.Fatalf("expected: %v, but got: %v", 2.0, median)
 	}
 
-	//	开始测试
-	for i, c := range cases {
-		t.Run(c.name+" "+strconv.Itoa(i), func(t *testing.T) {
-			got := Solution(c.inputs)
-			if !reflect.DeepEqual(got, c.expect) {
-				t.Fatalf("expected: %v, but got: %v, with inputs: %v",
-					c.expect, got, c.inputs)
-			}
-		})
+	// Test Case 2
+	medianFinder = Constructor()
+	medianFinder.AddNum(2)
+	medianFinder.AddNum(1)
+	median = medianFinder.FindMedian()
+	if !reflect.DeepEqual(median, 1.5) {
+		t.Fatalf("expected: %v, but got: %v", 1.5, median)
+	}
+	medianFinder.AddNum(5)
+	median = medianFinder.FindMedian()
+	if !reflect.DeepEqual(median, 2.0) {
+		t.Fatalf("expected: %v, but got: %v", 2.0, median)
+	}
+	medianFinder.AddNum(7)
+	medianFinder.AddNum(2)
+	median = medianFinder.FindMedian()
+	if !reflect.DeepEqual(median, 2.0) {
+		t.Fatalf("expected: %v, but got: %v", 2.0, median)
+	}
+	medianFinder.AddNum(0)
+	medianFinder.AddNum(5)
+	median = medianFinder.FindMedian()
+	if !reflect.DeepEqual(median, 2.0) {
+		t.Fatalf("expected: %v, but got: %v", 2.0, median)
 	}
 }