Merge pull request #912 from 0xff-dev/1552

Add solution and test-cases for problem 1552

Author: 6boris

leetcode/1501-1600/1552.Magnetic-Force-Between-Two-Balls/README.md

@@ -1,28 +1,29 @@
 # [1552.Magnetic Force Between Two Balls][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
+In the universe Earth C-137, Rick discovered a special form of magnetic force between two balls if they are put in his new invented basket. Rick has `n` empty baskets, the i<sup>th</sup> basket is at `position[i]`, Morty has `m` balls and needs to distribute the balls into the baskets such that the **minimum magnetic force** between any two balls is **maximum**.
 
-**Example 1:**
+Rick stated that magnetic force between two different balls at positions `x` and `y` is `|x - y|`.
 
-```
-Input: a = "11", b = "1"
-Output: "100"
-```
+Given the integer array `position` and the integer `m`. Return the required force.
 
-## 题意
-> ...
+**Example 1:**  
 
-## 题解
+![1](./q3v1.jpeg)
 
-### 思路1
-> ...
-Magnetic Force Between Two Balls
-```go
+```
+Input: position = [1,2,3,4,7], m = 3
+Output: 3
+Explanation: Distributing the 3 balls into baskets 1, 4 and 7 will make the magnetic force between ball pairs [3, 3, 6]. The minimum magnetic force is 3. We cannot achieve a larger minimum magnetic force than 3.
 ```
 
+**Example 2:**
+
+```
+Input: position = [5,4,3,2,1,1000000000], m = 2
+Output: 999999999
+Explanation: We can use baskets 1 and 1000000000.
+```
 
 ## 结语
 

leetcode/1501-1600/1552.Magnetic-Force-Between-Two-Balls/Solution.go

@@ -1,5 +1,38 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+import "sort"
+
+func canPlaceBalls(x int, position []int, m int) bool {
+	prevBallPos := position[0]
+	ballsPlaced := 1
+
+	for i := 1; i < len(position) && ballsPlaced < m; i++ {
+		currPos := position[i]
+		if currPos-prevBallPos >= x {
+			ballsPlaced++
+			prevBallPos = currPos
+		}
+	}
+
+	return ballsPlaced == m
+}
+
+func Solution(position []int, m int) int {
+	answer := 0
+	n := len(position)
+	sort.Ints(position)
+
+	low := 1
+	high := int(position[n-1]) / (m - 1)
+	for low <= high {
+		mid := low + (high-low)/2
+		if canPlaceBalls(mid, position, m) {
+			answer = mid
+			low = mid + 1
+		} else {
+			high = mid - 1
+		}
+	}
+
+	return answer
 }

leetcode/1501-1600/1552.Magnetic-Force-Between-Two-Balls/Solution_test.go

@@ -10,30 +10,30 @@ func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
 		name   string
-		inputs bool
-		expect bool
+		p      []int
+		m      int
+		expect int
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", []int{1, 2, 3, 4, 7}, 3, 3},
+		{"TestCase2", []int{5, 4, 3, 2, 1, 1000000000}, 2, 999999999},
 	}
 
 	//	开始测试
 	for i, c := range cases {
 		t.Run(c.name+" "+strconv.Itoa(i), func(t *testing.T) {
-			got := Solution(c.inputs)
+			got := Solution(c.p, c.m)
 			if !reflect.DeepEqual(got, c.expect) {
-				t.Fatalf("expected: %v, but got: %v, with inputs: %v",
-					c.expect, got, c.inputs)
+				t.Fatalf("expected: %v, but got: %v, with inputs: %v %v",
+					c.expect, got, c.p, c.m)
 			}
 		})
 	}
 }
 
-//	压力测试
+// 压力测试
 func BenchmarkSolution(b *testing.B) {
 }
 
-//	使用案列
+// 使用案列
 func ExampleSolution() {
 }