Add solution and test-cases for problem 3494

leetcode/3401-3500/3494.Find-the-Minimum-Amount-of-Time-to-Brew-Potions/README.md

@@ -1,28 +1,49 @@
 # [3494.Find the Minimum Amount of Time to Brew Potions][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
+You are given two integer arrays, `skill` and `mana`, of length `n` and `m`, respectively.
+
+In a laboratory, `n` wizards must brew `m` potions in order. Each potion has a mana capacity `mana[j]` and **must** pass through **all** the wizards sequentially to be brewed properly. The time taken by the `ith` wizard on the `jth` potion is `timeij = skill[i] * mana[j]`.
+
+Since the brewing process is delicate, a potion **must** be passed to the next wizard immediately after the current wizard completes their work. This means the timing must be synchronized so that each wizard begins working on a potion **exactly** when it arrives.
+
+Return the **minimum** amount of time required for the potions to be brewed properly.
 
-**Example 1:**
+**Example 1:**  
+
+![1](./1.png)
 
 ```
-Input: a = "11", b = "1"
-Output: "100"
+Input: skill = [1,5,2,4], mana = [5,1,4,2]
+
+Output: 110
+
+Explanation:
+
+As an example for why wizard 0 cannot start working on the 1st potion before time t = 52, consider the case where the wizards started preparing the 1st potion at time t = 50. At time t = 58, wizard 2 is done with the 1st potion, but wizard 3 will still be working on the 0th potion till time t = 60.
 ```
 
-## 题意
-> ...
+**Exmaple 2:**
 
-## 题解
+```
+Input: skill = [1,1,1], mana = [1,1,1]
+
+Output: 5
 
-### 思路1
-> ...
-Find the Minimum Amount of Time to Brew Potions
-```go
+Explanation:
+
+Preparation of the 0th potion begins at time t = 0, and is completed by time t = 3.
+Preparation of the 1st potion begins at time t = 1, and is completed by time t = 4.
+Preparation of the 2nd potion begins at time t = 2, and is completed by time t = 5.
 ```
 
+**Example 3:**
+
+```
+Input: skill = [1,2,3,4], mana = [1,2]
+
+Output: 21
+```
 
 ## 结语
 

leetcode/3401-3500/3494.Find-the-Minimum-Amount-of-Time-to-Brew-Potions/Solution.go

@@ -1,5 +1,42 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+func Solution(skill []int, mana []int) int64 {
+	N, M := len(skill), len(mana)
+	prevPotion := make([]int64, N)
+	for potion := 0; potion < M; potion++ {
+		var startTime int64
+		if potion > 0 {
+			// Need to find the min time in between these two to start
+			start, end := prevPotion[0], prevPotion[N-1]
+			for start <= end {
+				mid := start + (end-start)/2
+				if canCompletePotion(mid, potion, prevPotion, skill, mana) {
+					startTime = mid
+					end = mid - 1
+				} else {
+					start = mid + 1
+				}
+			}
+		}
+		for wiz := 0; wiz < N; wiz++ {
+			prevPotion[wiz] = startTime + int64(skill[wiz])*int64(mana[potion])
+			startTime = prevPotion[wiz]
+		}
+	}
+	return prevPotion[N-1]
+}
+
+func canCompletePotion(startTime int64, potionCount int, prevPotion []int64, skill, mana []int) bool {
+	for wizard := 0; wizard < len(skill); wizard++ {
+		doneTime := startTime + int64(skill[wizard])*int64(mana[potionCount])
+		// If the done time for the previous potion is greater than this one
+		// it means we cannot hand off this potion to the next wizard in a sequential
+		// manner.
+		if prevPotion[wizard] > startTime {
+			return false
+		}
+		startTime = doneTime
+	}
+	// As long as all potions are done after the previous, we are ok.
+	return true
 }

leetcode/3401-3500/3494.Find-the-Minimum-Amount-of-Time-to-Brew-Potions/Solution_test.go

@@ -9,31 +9,31 @@ import (
 func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
-		name   string
-		inputs bool
-		expect bool
+		name        string
+		skill, mana []int
+		expect      int64
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", []int{1, 5, 2, 4}, []int{5, 1, 4, 2}, 110},
+		{"TestCase2", []int{1, 1, 1}, []int{1, 1, 1}, 5},
+		{"TestCase3", []int{1, 2, 3, 4}, []int{1, 2}, 21},
 	}
 
 	//	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.skill, c.mana)
 			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.skill, c.mana)
 			}
 		})
 	}
 }
 
-//	压力测试
+// 压力测试
 func BenchmarkSolution(b *testing.B) {
 }
 
-//	使用案列
+// 使用案列
 func ExampleSolution() {
 }