添加 problem 128

Algorithms/0128. Longest Consecutive Sequence/128. Longest Consecutive Sequence.go

@@ -0,0 +1,97 @@
+package leetcode
+
+// 解法一 map，时间复杂度 O(n)
+func longestConsecutive(nums []int) int {
+	res, numMap := 0, map[int]int{}
+	for _, num := range nums {
+		if numMap[num] == 0 {
+			left, right, sum := 0, 0, 0
+			if numMap[num-1] > 0 {
+				left = numMap[num-1]
+			} else {
+				left = 0
+			}
+			if numMap[num+1] > 0 {
+				right = numMap[num+1]
+			} else {
+				right = 0
+			}
+			// sum: length of the sequence n is in
+			sum = left + right + 1
+			numMap[num] = sum
+			// keep track of the max length
+			res = max(res, sum)
+			// extend the length to the boundary(s) of the sequence
+			// will do nothing if n has no neighbors
+			numMap[num-left] = sum
+			numMap[num+right] = sum
+		} else {
+			continue
+		}
+	}
+	return res
+}
+
+// 解法二 并查集
+func longestConsecutive1(nums []int) int {
+	if len(nums) == 0 {
+		return 0
+	}
+	numMap, countMap, lcs, uf := map[int]int{}, map[int]int{}, 0, UnionFind{}
+	uf.init(len(nums))
+	for i := 0; i < len(nums); i++ {
+		countMap[i] = 1
+	}
+	for i := 0; i < len(nums); i++ {
+		if _, ok := numMap[nums[i]]; ok {
+			continue
+		}
+		numMap[nums[i]] = i
+		if _, ok := numMap[nums[i]+1]; ok {
+			uf.union(i, numMap[nums[i]+1])
+		}
+		if _, ok := numMap[nums[i]-1]; ok {
+			uf.union(i, numMap[nums[i]-1])
+		}
+	}
+	for key := range countMap {
+		parent := uf.find(key)
+		if parent != key {
+			countMap[parent]++
+		}
+		if countMap[parent] > lcs {
+			lcs = countMap[parent]
+		}
+	}
+	return lcs
+}
+
+// 解法三 暴力解法，时间复杂度 O(n^2)
+func longestConsecutive2(nums []int) int {
+	if len(nums) == 0 {
+		return 0
+	}
+	numMap, length, tmp, lcs := map[int]bool{}, 0, 0, 0
+	for i := 0; i < len(nums); i++ {
+		numMap[nums[i]] = true
+	}
+	for key := range numMap {
+		if !numMap[key-1] && !numMap[key+1] {
+			delete(numMap, key)
+		}
+	}
+	if len(numMap) == 0 {
+		return 1
+	}
+	for key := range numMap {
+		if !numMap[key-1] && numMap[key+1] {
+			length, tmp = 1, key+1
+			for numMap[tmp] {
+				length++
+				tmp++
+			}
+			lcs = max(lcs, length)
+		}
+	}
+	return max(lcs, length)
+}

Algorithms/0128. Longest Consecutive Sequence/128. Longest Consecutive Sequence_test.go

@@ -0,0 +1,62 @@
+package leetcode
+
+import (
+	"fmt"
+	"testing"
+)
+
+type question128 struct {
+	para128
+	ans128
+}
+
+// para 是参数
+// one 代表第一个参数
+type para128 struct {
+	one []int
+}
+
+// ans 是答案
+// one 代表第一个答案
+type ans128 struct {
+	one int
+}
+
+func Test_Problem128(t *testing.T) {
+
+	qs := []question128{
+
+		question128{
+			para128{[]int{}},
+			ans128{0},
+		},
+
+		question128{
+			para128{[]int{0}},
+			ans128{1},
+		},
+
+		question128{
+			para128{[]int{9, 1, 4, 7, 3, -1, 0, 5, 8, -1, 6}},
+			ans128{7},
+		},
+
+		question128{
+			para128{[]int{2147483646, -2147483647, 0, 2, 2147483644, -2147483645, 2147483645}},
+			ans128{3},
+		},
+
+		question128{
+			para128{[]int{100, 4, 200, 1, 3, 2}},
+			ans128{4},
+		},
+	}
+
+	fmt.Printf("------------------------Leetcode Problem 128------------------------\n")
+
+	for _, q := range qs {
+		_, p := q.ans128, q.para128
+		fmt.Printf("【input】:%v       【output】:%v\n", p, longestConsecutive(p.one))
+	}
+	fmt.Printf("\n\n\n")
+}