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top-100-liked/10_test.go

@@ -0,0 +1,28 @@
+package top100liked
+
+import "testing"
+
+// https://leetcode.cn/problems/subarray-sum-equals-k/description/?envType=study-plan-v2&envId=top-100-liked
+// 这题好难，理解不能
+
+func subarraySum(nums []int, k int) int {
+	freq := make(map[int]int)
+	freq[0] = 1
+	cur := 0
+	res := 0
+	for _, v := range nums {
+		cur += v
+		if f, ok := freq[cur-k]; ok {
+			res += f
+		}
+		freq[cur]++
+	}
+	return res
+}
+
+func TestS10(t *testing.T) {
+	println(subarraySum([]int{1, 1, 1}, 2))
+	println(subarraySum([]int{1, 2, 3}, 3))
+	println(subarraySum([]int{1}, 0))
+	println(subarraySum([]int{-1, -1, 1}, 0))
+}