algorithm004-01 · shiyibo · Dec 15, 2019 · Dec 15, 2019 · Dec 15, 2019
diff --git a/Week 06/id_531/leetCode_208_531.go b/Week 06/id_531/leetCode_208_531.go
@@ -0,0 +1,70 @@
+package id_531
+
+type Node struct {
+	isWord bool
+	next   map[string]*Node
+}
+
+func NewNode() *Node {
+	return &Node{next: make(map[string]*Node)}
+}
+
+type Trie struct {
+	root *Node
+}
+
+func Constructor() Trie {
+	return Trie{root: NewNode()}
+}
+
+func (t *Trie) Insert(word string) {
+	add(t.root, word, 0)
+}
+
+func add(node *Node, word string, index int) {
+	if index == len(word) {
+		if !node.isWord {
+			node.isWord = true
+		}
+		return
+	}
+
+	c := string([]rune(word)[index])
+	if node.next[c] == nil {
+		node.next[c] = NewNode()
+	}
+	add(node.next[c], word, index+1)
+}
+
+func (t *Trie) Search(word string) bool {
+	return contains(t.root, word, 0)
+}
+
+func contains(node *Node, word string, index int) bool {
+	if index == len(word) {
+		return node.isWord
+	}
+
+	c := string([]rune(word)[index])
+	if node.next[c] == nil {
+		return false
+	}
+	return contains(node.next[c], word, index+1)
+}
+
+func (t *Trie) StartsWith(prefix string) bool {
+	return isPrefix(t.root, prefix, 0)
+}
+
+func isPrefix(node *Node, prefix string, index int) bool {
+	if index == len(prefix) {
+		return true
+	}
+
+	c := string([]rune(prefix)[index])
+	if node.next[c] == nil {
+		return false
+	}
+
+	return isPrefix(node.next[c], prefix, index+1)
+}
diff --git a/Week 06/id_531/leetCode_51_531.go b/Week 06/id_531/leetCode_51_531.go
@@ -0,0 +1,60 @@
+package id_531
+
+func solveNQueens(n int) [][]string {
+	if n == 0 {
+		return nil
+	}
+	res := make([][]int, 0)
+	//存放列，撇，捺
+	cols := make(map[int]bool, n)
+	pies := make(map[int]bool, n)
+	nas := make(map[int]bool, n)
+	dfs([]int{}, n, cols, pies, nas, &res)
+	return generateResult(res, n)
+}
+
+func dfs(rows []int, n int, cols, pies, nas map[int]bool, res *[][]int) {
+	//出递归的条件
+	row := len(rows)
+	if row == n {
+		tmp := make([]int, len(rows))
+		copy(tmp, rows)
+		*res = append(*res, tmp)
+		return
+	}
+	//对于每一层就遍历所有的列
+	for col := 0; col < n; col++ {
+		//当列，撇，捺中都不存在对应的值时，将其加入
+		if !cols[col] && !pies[row+col] && !nas[row-col] {
+			//开始更新列撇捺的值
+			cols[col] = true
+			pies[row+col] = true
+			nas[row-col] = true
+			//递归执行下一层操作
+			dfs(append(rows, col), n, cols, pies, nas, res)
+			//每一次递归完成后将原有的标志位清空,以方便下一层搜索
+			cols[col] = false
+			pies[row+col] = false
+			nas[row-col] = false
+		}
+	}
+}
+
+func generateResult(res [][]int, n int) (result [][]string) {
+	for _, v := range res {
+		var s []string
+		for _, val := range v {
+			str := ""
+			for i := 0; i < n; i++ {
+				if i == val {
+					str += "Q"
+				} else {
+					str += "."
+				}
+			}
+			s = append(s, str)
+		}
+		result = append(result, s)
+	}
+	return
+}
diff --git a/Week 07/id_531/leetCode_493_531.go b/Week 07/id_531/leetCode_493_531.go
@@ -0,0 +1,37 @@
+package id_531
+
+func reversePairs(nums []int) int {
+	return mergeSort(nums, 0, len(nums)-1)
+}
+
+func mergeSort(nums []int, left, right int) int {
+	if left >= right {
+		return 0
+	}
+	mid := left + (right-left)/2
+	count := mergeSort(nums, left, mid) + mergeSort(nums, mid+1, right)
+	cache := make([]int, right-left+1)
+	i := left
+	t := left
+	c := 0
+	for j := mid + 1; j < right; j++ {
+		for i <= mid && nums[i] <= 2*nums[j] {
+			i++
+		}
+		for t <= mid && nums[t] < nums[j] {
+			c++
+			t++
+			cache[c] = nums[t]
+		}
+		cache[c] = nums[j]
+		count += mid - i + 1
+		c++
+	}
+	for t <= mid {
+		c++
+		t++
+		cache[c] = nums[t]
+	}
+	copy(nums, cache)
+	return count
+}
diff --git a/Week 07/id_531/leetCode_56_531.go b/Week 07/id_531/leetCode_56_531.go
@@ -0,0 +1,45 @@
+package id_531
+
+import "sort"
+
+type ByRow [][]int
+
+func (b ByRow) Len() int {
+	return len(b)
+}
+
+func (b ByRow) Swap(i, j int) {
+	b[i], b[j] = b[j], b[i]
+}
+
+func (b ByRow) Less(i, j int) bool {
+	return b[i][0] < b[j][0]
+}
+
+func merge(intervals [][]int) [][]int {
+	res := make([][]int, 0)
+	if len(intervals) == 0 {
+		return res
+	}
+	sort.Sort(ByRow(intervals))
+	tmp := make([]int, 2)
+	tmp[0] = intervals[0][0]
+	tmp[1] = intervals[0][1]
+
+	for i := 1; i < len(intervals); i++ {
+
+		if tmp[1] >= intervals[i][0] {
+			if tmp[1] < intervals[i][1] {
+				tmp[1] = intervals[i][1]
+			}
+		} else {
+			res = append(res, []int{tmp[0], tmp[1]})
+			tmp[0] = intervals[i][0]
+			tmp[1] = intervals[i][1]
+		}
+	}
+
+	res = append(res, []int{tmp[0], tmp[1]})
+
+	return res
+}
diff --git a/Week 08/id_531/NOTE.md b/Week 08/id_531/NOTE.md
@@ -0,0 +1,4 @@
+# NOTE
+
+
+
diff --git a/Week 08/id_531/leetCode_300_531.go b/Week 08/id_531/leetCode_300_531.go
@@ -0,0 +1,52 @@
+package id_531
+
+type state struct {
+	s [][]int
+}
+
+func (s *state) Add(n int) {
+	ok := true
+	for i, l := range s.s {
+		if n >= l[0] {
+			ok = false
+		}
+		if n > l[len(l)-1] {
+			s.s[i] = append(l, n)
+		} else {
+			if len(l)-2 < 0 || len(l)-2 >= 0 && n > l[len(l)-2] {
+				l[len(l)-1] = n
+			}
+			s.s[i] = l
+		}
+	}
+	if ok {
+		// fmt.Printf("%v ?? %v \n", n, s.s)
+		s.s = append(s.s, []int{n})
+	}
+}
+func (s *state) Res() int {
+	max := 0
+	for _, l := range s.s {
+		if len(l) > max {
+			max = len(l)
+		}
+	}
+	return max
+}
+func lengthOfLIS(nums []int) int {
+	if len(nums) <= 1 {
+		return len(nums)
+	}
+	s := &state{}
+
+	for i, n := range nums {
+		if i == 0 {
+			s = &state{s: [][]int{{n}}}
+			continue
+		}
+		s.Add(n)
+
+	}
+	ans := s.Res()
+	return ans
+}
diff --git a/Week 08/id_531/leetCode_387_531.go b/Week 08/id_531/leetCode_387_531.go
@@ -0,0 +1,18 @@
+package id_531
+
+func firstUniqChar(s string) int {
+	m := make(map[int32]int)
+	for _, a := range s {
+		if c, ok := m[a]; ok {
+			m[a] = c + 1
+		} else {
+			m[a] = 1
+		}
+	}
+	for i, a := range s {
+		if m[a] == 1 {
+			return i
+		}
+	}
+	return -1
+}