diff --git a/leetcode/3501-3600/3583.Count-Special-Triplets/README.md b/leetcode/3501-3600/3583.Count-Special-Triplets/README.md index 6ce577ba5..aa47f5fe0 100755 --- a/leetcode/3501-3600/3583.Count-Special-Triplets/README.md +++ b/leetcode/3501-3600/3583.Count-Special-Triplets/README.md @@ -1,28 +1,70 @@ # [3583.Count Special Triplets][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 an integer array `nums`. + +A **special triplet** is defined as a triplet of indices `(i, j, k)` such that: + +- `0 <= i < j < k < n`, where `n = nums.length` +- `nums[i] == nums[j] * 2` +- `nums[k] == nums[j] * 2` + +Return the total number of **special triplets** in the array. + +Since the answer may be large, return it **modulo** `10^9 + 7`. **Example 1:** ``` -Input: a = "11", b = "1" -Output: "100" +Input: nums = [6,3,6] + +Output: 1 + +Explanation: + +The only special triplet is (i, j, k) = (0, 1, 2), where: + +nums[0] = 6, nums[1] = 3, nums[2] = 6 +nums[0] = nums[1] * 2 = 3 * 2 = 6 +nums[2] = nums[1] * 2 = 3 * 2 = 6 +``` + +**Example 2:** + ``` +Input: nums = [0,1,0,0] + +Output: 1 + +Explanation: + +The only special triplet is (i, j, k) = (0, 2, 3), where: -## 题意 -> ... +nums[0] = 0, nums[2] = 0, nums[3] = 0 +nums[0] = nums[2] * 2 = 0 * 2 = 0 +nums[3] = nums[2] * 2 = 0 * 2 = 0 +``` -## 题解 +**Example 3:** -### 思路1 -> ... -Count Special Triplets -```go ``` +Input: nums = [8,4,2,8,4] + +Output: 2 + +Explanation: +There are exactly two special triplets: + +(i, j, k) = (0, 1, 3) +nums[0] = 8, nums[1] = 4, nums[3] = 8 +nums[0] = nums[1] * 2 = 4 * 2 = 8 +nums[3] = nums[1] * 2 = 4 * 2 = 8 +(i, j, k) = (1, 2, 4) +nums[1] = 4, nums[2] = 2, nums[4] = 4 +nums[1] = nums[2] * 2 = 2 * 2 = 4 +nums[4] = nums[2] * 2 = 2 * 2 = 4 +``` ## 结语 diff --git a/leetcode/3501-3600/3583.Count-Special-Triplets/Solution.go b/leetcode/3501-3600/3583.Count-Special-Triplets/Solution.go index d115ccf5e..0baaa7e74 100644 --- a/leetcode/3501-3600/3583.Count-Special-Triplets/Solution.go +++ b/leetcode/3501-3600/3583.Count-Special-Triplets/Solution.go @@ -1,5 +1,23 @@ package Solution -func Solution(x bool) bool { - return x +func Solution(nums []int) int { + const MOD = 1000000007 + numCnt := make(map[int]int) + numPartialCnt := make(map[int]int) + + for _, v := range nums { + numCnt[v]++ + } + + ans := 0 + for _, v := range nums { + target := v * 2 + lCnt := numPartialCnt[target] + numPartialCnt[v]++ + rCnt := numCnt[target] - numPartialCnt[target] + + ans = (ans + lCnt*rCnt) % MOD + } + + return ans } diff --git a/leetcode/3501-3600/3583.Count-Special-Triplets/Solution_test.go b/leetcode/3501-3600/3583.Count-Special-Triplets/Solution_test.go index 14ff50eb4..c5a33456a 100644 --- a/leetcode/3501-3600/3583.Count-Special-Triplets/Solution_test.go +++ b/leetcode/3501-3600/3583.Count-Special-Triplets/Solution_test.go @@ -10,12 +10,12 @@ func TestSolution(t *testing.T) { // 测试用例 cases := []struct { name string - inputs bool - expect bool + inputs []int + expect int }{ - {"TestCase", true, true}, - {"TestCase", true, true}, - {"TestCase", false, false}, + {"TestCase1", []int{6, 3, 6}, 1}, + {"TestCase2", []int{0, 1, 0, 0}, 1}, + {"TestCase3", []int{8, 4, 2, 8, 4}, 2}, } // 开始测试 @@ -30,10 +30,10 @@ 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() { }