Merge pull request #2517 from tedkimdev/tedkimdev/week6

[tedkimdev] WEEK 06 Solutions

Author: tedkimdev

container-with-most-water/tedkimdev.rs

@@ -0,0 +1,19 @@
+// TC: O(n)
+// SC: O(1)
+impl Solution {
+    pub fn max_area(heights: Vec<i32>) -> i32 {
+        let (mut left, mut right) = (0, heights.len() - 1);
+        let mut res = 0i32;
+        while left <= right {
+            res = res.max(((right - left) as i32) * heights[left].min(heights[right]));
+
+            if heights[right] < heights[left] {
+                right -= 1;
+            } else {
+                left += 1;
+            }
+        }
+
+        res
+    }
+}

design-add-and-search-words-data-structure/tedkimdev.go

@@ -0,0 +1,56 @@
+type WordDictionary struct {
+	root *TrieNode
+}
+
+func Constructor() WordDictionary {
+	return WordDictionary{root: NewTrieNode()}
+}
+
+// TC: O(n)
+// SC: O(t + n)
+// t = total number of TrieNodes created so far
+func (this *WordDictionary) AddWord(word string) {
+	cur := this.root
+	for _, c := range word {
+		if cur.Children[c-'a'] == nil {
+			cur.Children[c-'a'] = NewTrieNode()
+		}
+		cur = cur.Children[c-'a']
+	}
+	cur.IsWord = true
+}
+
+// TC: O(n)
+func (this *WordDictionary) Search(word string) bool {
+	return this.dfs(word, 0, this.root)
+}
+
+func (this *WordDictionary) dfs(word string, index int, root *TrieNode) bool {
+	cur := root
+	for i := index; i < len(word); i++ {
+		c := word[i]
+		if c == '.' {
+			for _, child := range cur.Children {
+				if child != nil && this.dfs(word, i+1, child) {
+					return true
+				}
+			}
+			return false
+		} else {
+			if cur.Children[c-'a'] == nil {
+				return false
+			}
+			cur = cur.Children[c-'a']
+		}
+	}
+	return cur.IsWord
+}
+
+type TrieNode struct {
+	Children [26]*TrieNode
+	IsWord   bool
+}
+
+func NewTrieNode() *TrieNode {
+	return &TrieNode{}
+}

longest-increasing-subsequence/tedkimdev.go

@@ -0,0 +1,32 @@
+// TC: O(n ^ 2)
+// SC: O(n)
+func lengthOfLIS(nums []int) int {
+	dp := make([]int, len(nums))
+
+	for i := range dp {
+		dp[i] = 1
+	}
+
+	for i := len(nums) - 2; i >= 0; i-- {
+		for j := i + 1; j < len(nums); j++ {
+			if nums[i] < nums[j] {
+				if dp[i] < 1+dp[j] {
+					dp[i] = 1 + dp[j]
+				}
+			}
+		}
+	}
+
+	maxLength := 1
+	for _, length := range dp {
+		maxLength = max(maxLength, length)
+	}
+	return maxLength
+}
+
+func max(a, b int) int {
+	if a > b {
+		return a
+	}
+	return b
+}

spiral-matrix/tedkimdev.rs

@@ -0,0 +1,38 @@
+// TC: O(m * n)
+// SC: O(m * n)
+impl Solution {
+    pub fn spiral_order(matrix: Vec<Vec<i32>>) -> Vec<i32> {
+        let mut result: Vec<i32> = Vec::new();
+
+        let mut left = 0i32;
+        let mut right = matrix[0].len() as i32;
+        let mut top = 0i32;
+        let mut bottom = matrix.len() as i32;
+
+        while left < right && top < bottom {
+            for i in left..right {
+                result.push(matrix[top as usize][i as usize]);
+            }
+            top += 1;
+            for i in top..bottom {
+                result.push(matrix[i as usize][(right - 1) as usize]);
+            }
+            right -= 1;
+
+            if !(left < right && top < bottom) {
+                break;
+            }
+
+            for i in (left..right).rev() {
+                result.push(matrix[(bottom - 1) as usize][i as usize]);
+            }
+            bottom -= 1;
+            for i in (top..bottom).rev() {
+                result.push(matrix[i as usize][left as usize]);
+            }
+            left += 1;
+        }
+
+        result
+    }
+}

valid-parentheses/tedkimdev.rs

@@ -0,0 +1,33 @@
+// TC: O(n)
+// SC: O(n)
+impl Solution {
+    pub fn is_valid(s: String) -> bool {
+		let mut stack = Vec::new();
+
+		for c in s.chars() {
+			match c {
+				'{' | '(' | '[' => {
+					stack.push(c);
+				},
+				'}' => {
+					if Some('{') != stack.pop() {
+						return false;
+					}
+				},
+				')' => {
+					if Some('(') != stack.pop() {
+						return false;
+					}
+				},
+				']' => {
+					if Some('[') != stack.pop() {
+						return false;
+					}
+				},
+				_ => {},
+			};
+		}
+
+		stack.is_empty()
+    }
+}