Add solution and test-cases for problem 3186

Author: 0xff-dev

leetcode/3101-3200/3186.Maximum-Total-Damage-With-Spell-Casting/README.md

@@ -1,28 +1,39 @@
 # [3186.Maximum Total Damage With Spell Casting][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
+A magician has various spells.
+
+You are given an array `power`, where each element represents the damage of a spell. Multiple spells can have the same damage value.
+
+It is a known fact that if a magician decides to cast a spell with a damage of `power[i]`, they **cannot** cast any spell with a damage of `power[i] - 2`, `power[i] - 1`, `power[i] + 1`, or `power[i] + 2`.
+
+Each spell can be cast **only once**.
+
+Return the **maximum** possible total damage that a magician can cast.
 
 **Example 1:**
 
 ```
-Input: a = "11", b = "1"
-Output: "100"
-```
+Input: power = [1,1,3,4]
 
-## 题意
-> ...
+Output: 6
 
-## 题解
+Explanation:
 
-### 思路1
-> ...
-Maximum Total Damage With Spell Casting
-```go
+The maximum possible damage of 6 is produced by casting spells 0, 1, 3 with damage 1, 1, 4.
 ```
 
+**Example 2:**
+
+```
+Input: power = [7,1,6,6]
+
+Output: 13
+
+Explanation:
+
+The maximum possible damage of 13 is produced by casting spells 1, 2, 3 with damage 1, 6, 6.
+```
 
 ## 结语
 

leetcode/3101-3200/3186.Maximum-Total-Damage-With-Spell-Casting/Solution.go

@@ -1,5 +1,78 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+import "sort"
+
+func Solution(power []int) int64 {
+	if len(power) == 0 {
+		return 0
+	}
+
+	// 1. Calculate Total Damage per Value and collect unique damage values.
+	damageSums := make(map[int]int64)
+	for _, p := range power {
+		damageSums[p] += int64(p)
+	}
+
+	// Get all unique damage values and sort them.
+	var uniqueDamages []int
+	for d := range damageSums {
+		uniqueDamages = append(uniqueDamages, d)
+	}
+	sort.Ints(uniqueDamages)
+
+	M := len(uniqueDamages)
+	if M == 0 {
+		return 0
+	}
+
+	// 2. Dynamic Programming Array F.
+	// F[i] stores the max total damage considering spells with damage
+	// up to and including uniqueDamages[i].
+	F := make([]int64, M)
+
+	// F[0] Base Case:
+	F[0] = damageSums[uniqueDamages[0]]
+
+	// 3. DP Iteration:
+	for i := 1; i < M; i++ {
+		currentDamage := uniqueDamages[i]
+		D_i := damageSums[currentDamage]
+
+		// Option 1: Skip spells of currentDamage.
+		// Max damage is F[i-1].
+		skipDamage := F[i-1]
+
+		// Option 2: Cast all spells of currentDamage.
+		// Gain D_i. Must add to the max damage achieved up to damage currentDamage - 3.
+
+		// Find the index 'j' of the *largest* unique damage value <= currentDamage - 3.
+		// We use sort.Search to find the first element > currentDamage - 3, then step back.
+
+		target := currentDamage - 3
+
+		// Search for the first index 'k' where uniqueDamages[k] > target.
+		// Since sort.Search is not available for a custom search over a slice
+		// and we need to find the index for uniqueDamages, we use sort.SearchInts
+		// which is equivalent to finding the insertion point.
+
+		// 'k' is the index of the first element STRICTLY GREATER THAN target.
+		k := sort.SearchInts(uniqueDamages, target+1)
+
+		// The index of the largest element <= target is k-1.
+		j := k - 1
+
+		var prevMaxDamage int64 // Will be 0 if no such spell exists (j < 0).
+		if j >= 0 {
+			// prevMaxDamage is the max damage considering spells up to uniqueDamages[j].
+			prevMaxDamage = F[j]
+		}
+
+		castDamage := D_i + prevMaxDamage
+
+		// F[i] = max(Option 1, Option 2)
+		F[i] = max(skipDamage, castDamage)
+	}
+
+	// The result is the maximum damage considering all unique damage values.
+	return F[M-1]
 }

leetcode/3101-3200/3186.Maximum-Total-Damage-With-Spell-Casting/Solution_test.go

@@ -10,12 +10,11 @@ func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
 		name   string
-		inputs bool
-		expect bool
+		inputs []int
+		expect int64
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", []int{1, 1, 3, 4}, 6},
+		{"TestCase2", []int{7, 1, 6, 6}, 13},
 	}
 
 	//	开始测试
@@ -30,10 +29,10 @@ func TestSolution(t *testing.T) {
 	}
 }
 
-//	压力测试
+// 压力测试
 func BenchmarkSolution(b *testing.B) {
 }
 
-//	使用案列
+// 使用案列
 func ExampleSolution() {
 }