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top-100-liked/17_test.go

@@ -0,0 +1,31 @@
+package top100liked
+
+import "testing"
+
+// https://leetcode.cn/problems/first-missing-positive/description/?envType=study-plan-v2&envId=top-100-liked
+
+func firstMissingPositive(nums []int) int {
+	n := len(nums)
+	for i := range nums {
+		for nums[i] >= 1 && nums[i] <= n && nums[i] != i+1 {
+			if nums[i] != nums[nums[i]-1] { // 关键条件，否则会死循环 [1, 1]
+				nums[i], nums[nums[i]-1] = nums[nums[i]-1], nums[i]
+			} else {
+				break
+			}
+		}
+	}
+	for i, v := range nums {
+		if v != i+1 {
+			return i + 1
+		}
+	}
+	return n + 1
+}
+
+func TestS17(t *testing.T) {
+	// println(firstMissingPositive([]int{1, 2, 0}))
+	// println(firstMissingPositive([]int{3, 4, -1, 1}))
+	// println(firstMissingPositive([]int{7, 8, 9, 11, 12}))
+	println(firstMissingPositive([]int{1, 1}))
+}