第三周作业#29

Week_03/id_29/Leetcode_104_29.go

@@ -0,0 +1,14 @@
+package main
+
+func maxDepth(root *TreeNode) int {
+	if root == nil {
+		return 0
+	}
+	leftDepth := maxDepth(root.Left)
+	rightDepth := maxDepth(root.Right)
+	if leftDepth > rightDepth {
+		return leftDepth + 1
+	} else {
+		return rightDepth + 1
+	}
+}

Week_03/id_29/Leetcode_111_29.go

@@ -0,0 +1,29 @@
+package main
+
+func minDepth(root *TreeNode) int {
+	if root == nil {
+		return 0
+	}
+	left := minDepth(root.Left)
+	right := minDepth(root.Right)
+	if left == 0 || right == 0 {
+		return 1 + max(left, right)
+	}
+	return 1 + min(left, right)
+}
+
+func min(x, y int) int {
+	if x >= y {
+		return y
+	} else {
+		return x
+	}
+}
+
+func max(x, y int) int {
+	if x <= y {
+		return y
+	} else {
+		return x
+	}
+}

Week_03/id_29/Leetcode_200_29.go

@@ -0,0 +1,46 @@
+package main
+
+func numIslands(grid [][]byte) int {
+	color := 1
+	colors := make([][]int, len(grid))
+	for x := range colors {
+		colors[x] = make([]int, len(grid[x]))
+	}
+
+	for x := range grid {
+		for y := range grid[x] {
+			marked := markColor(x, y, grid, colors, color)
+			if marked {
+				color++
+			}
+		}
+	}
+
+	return color - 1
+}
+
+func markColor(x, y int, grid [][]byte, colors [][]int, color int) bool {
+	if x < 0 || x >= len(grid) {
+		return false
+	}
+
+	if y < 0 || y >= len(grid[x]) {
+		return false
+	}
+
+	if colors[x][y] != 0 {
+		return false
+	}
+
+	if grid[x][y] == '0' {
+		colors[x][y] = -1
+		return false
+	}
+
+	colors[x][y] = color
+	markColor(x+1, y, grid, colors, color)
+	markColor(x-1, y, grid, colors, color)
+	markColor(x, y-1, grid, colors, color)
+	markColor(x, y+1, grid, colors, color)
+	return true
+}

Week_03/id_29/Leetcode_210_29.go

@@ -0,0 +1,37 @@
+package main
+
+func findOrder(numCourses int, prerequisites [][]int) []int {
+
+	queue := make([]int, 0, numCourses)
+	inDegree := make([]int, numCourses, numCourses)
+	graph := make(map[int][]int)
+
+	for _, edge := range prerequisites {
+		from, to := edge[1], edge[0]
+		inDegree[to]++
+		graph[from] = append(graph[from], to)
+	}
+
+	for i, n := range inDegree {
+		if n == 0 {
+			queue = append(queue, i)
+		}
+	}
+
+	for i := 0; i < numCourses; i++ {
+		if i >= len(queue) {
+			return []int{}
+		}
+		course := queue[i]
+		nextCourses := graph[course]
+
+		for _, next := range nextCourses {
+			inDegree[next]--
+			if inDegree[next] == 0 {
+				queue = append(queue, next)
+			}
+		}
+	}
+
+	return queue
+}

Week_03/id_29/Leetcode_703_29.go

@@ -0,0 +1,57 @@
+package main
+
+import "container/heap"
+
+type IntHeap []int
+
+type KthLargest struct {
+	k    int
+	heap intHeap
+}
+
+func Constructor(k int, nums []int) KthLargest {
+	h := intHeap(nums)
+	heap.Init(&h)
+
+	for len(h) > k {
+		heap.Pop(&h)
+	}
+
+	return KthLargest{
+		k:    k,
+		heap: h,
+	}
+}
+
+func (kl *KthLargest) Add(val int) int {
+	heap.Push(&kl.heap, val)
+
+	if len(kl.heap) > kl.k {
+		heap.Pop(&kl.heap)
+	}
+
+	return kl.heap[0]
+}
+
+type intHeap []int
+
+func (h intHeap) Len() int {
+	return len(h)
+}
+
+func (h intHeap) Less(i, j int) bool {
+	return h[i] < h[j]
+}
+
+func (h intHeap) Swap(i, j int) {
+	h[i], h[j] = h[j], h[i]
+}
+func (h *intHeap) Push(x interface{}) {
+	*h = append(*h, x.(int))
+}
+
+func (h *intHeap) Pop() interface{} {
+	res := (*h)[len(*h)-1]
+	*h = (*h)[:len(*h)-1]
+	return res
+}

Week_03/id_29/main.go

@@ -0,0 +1,11 @@
+package main
+
+func main() {
+
+}
+
+type TreeNode struct {
+	Val   int
+	Left  *TreeNode
+	Right *TreeNode
+}