规范格式

leetcode/0287.Find-the-Duplicate-Number/287. Find the Duplicate Number.go

@@ -0,0 +1,55 @@
+package leetcode
+
+import "sort"
+
+// 解法一 快慢指针
+func findDuplicate(nums []int) int {
+	slow := nums[0]
+	fast := nums[nums[0]]
+	for fast != slow {
+		slow = nums[slow]
+		fast = nums[nums[fast]]
+	}
+	walker := 0
+	for walker != slow {
+		walker = nums[walker]
+		slow = nums[slow]
+	}
+	return walker
+}
+
+// 解法二 二分搜索
+func findDuplicate1(nums []int) int {
+	low, high := 0, len(nums)-1
+	for low < high {
+		mid, count := low+(high-low)>>1, 0
+		for _, num := range nums {
+			if num <= mid {
+				count++
+			}
+		}
+		if count > mid {
+			high = mid
+		} else {
+			low = mid + 1
+		}
+	}
+	return low
+}
+
+// 解法三
+func findDuplicate2(nums []int) int {
+	if len(nums) == 0 {
+		return 0
+	}
+	sort.Ints(nums)
+	diff := -1
+	for i := 0; i < len(nums); i++ {
+		if nums[i]-i-1 >= diff {
+			diff = nums[i] - i - 1
+		} else {
+			return nums[i]
+		}
+	}
+	return 0
+}