Merge pull request #657 from 0xff-dev/1458

Add solution and test-cases for problem 1458

leetcode/1401-1500/1458.Max-Dot-Product-of-Two-Subsequences/README.md

@@ -0,0 +1,42 @@
+# [1458. Max Dot Product of Two Subsequences][title]
+
+## Description
+Given two arrays `nums1` and `nums2`.
+
+Return the maximum dot product between **non-empty** subsequences of nums1 and nums2 with the same length.
+
+A subsequence of a array is a new array which is formed from the original array by deleting some (can be none) of the characters without disturbing the relative positions of the remaining characters. (ie, [`2,3,5`] is a subsequence of [`1,2,3,4,5`] while [`1,5,3`] is not).
+
+**Example 1:**
+
+```
+Input: nums1 = [2,1,-2,5], nums2 = [3,0,-6]
+Output: 18
+Explanation: Take subsequence [2,-2] from nums1 and subsequence [3,-6] from nums2.
+Their dot product is (2*3 + (-2)*(-6)) = 18.
+```
+
+**Example 2:**
+
+```
+Input: nums1 = [3,-2], nums2 = [2,-6,7]
+Output: 21
+Explanation: Take subsequence [3] from nums1 and subsequence [7] from nums2.
+Their dot product is (3*7) = 21.
+```
+
+**Example 3:**
+
+```
+Input: nums1 = [-1,-1], nums2 = [1,1]
+Output: -1
+Explanation: Take subsequence [-1] from nums1 and subsequence [1] from nums2.
+Their dot product is -1.
+```
+
+## 结语
+
+如果你同我一样热爱数据结构、算法、LeetCode，可以关注我 GitHub 上的 LeetCode 题解：[awesome-golang-algorithm][me]
+
+[title]: https://leetcode.com/problems/max-dot-product-of-two-subsequences
+[me]: https://github.com/kylesliu/awesome-golang-algorithm

leetcode/1401-1500/1458.Max-Dot-Product-of-Two-Subsequences/Solution.go

@@ -1,5 +1,45 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+import (
+	"math"
+)
+
+func Solution(nums1 []int, nums2 []int) int {
+	l1, l2 := len(nums1), len(nums2)
+	dp := make([][]int, l1)
+	for i := 0; i < l1; i++ {
+		dp[i] = make([]int, l2)
+		for j := 0; j < l2; j++ {
+			dp[i][j] = math.MinInt
+		}
+	}
+	// -1, -1
+	// 1, 1
+	//bool是否确定返回的0是否是因为到了边界导致的, 上面的测试用例就是例子，应该返回-1，但是遇到了边界导致返回0，结果不对
+	var dfs func(int, int) (int, bool)
+	dfs = func(i, j int) (int, bool) {
+		if i == l1 || j == l2 {
+			return 0, false
+		}
+		if dp[i][j] != math.MinInt {
+			return dp[i][j], true
+		}
+		a := nums1[i] * nums2[j]
+
+		if b, ok := dfs(i+1, j+1); ok && b > 0 {
+			a += b
+		}
+		// 因为到了边界，返回的0，导致比-1大
+		if c, ok := dfs(i, j+1); ok && c > a {
+			a = c
+		}
+		if d, ok := dfs(i+1, j); ok && d > a {
+			a = d
+		}
+		dp[i][j] = a
+		return a, true
+	}
+
+	a, _ := dfs(0, 0)
+	return a
 }

leetcode/1401-1500/1458.Max-Dot-Product-of-Two-Subsequences/Solution_test.go

@@ -10,30 +10,30 @@ func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
 		name   string
-		inputs bool
-		expect bool
+		n1, n2 []int
+		expect int
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", []int{2, 1, -2, 5}, []int{3, 0, -6}, 18},
+		{"TestCase2", []int{3, -2}, []int{2, -6, 7}, 21},
+		{"TestCase3", []int{-1, -1}, []int{1, 1}, -1},
 	}
 
 	//	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.n1, c.n2)
 			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.n1, c.n2)
 			}
 		})
 	}
 }
 
-//	压力测试
+// 压力测试
 func BenchmarkSolution(b *testing.B) {
 }
 
-//	使用案列
+// 使用案列
 func ExampleSolution() {
 }