Merge pull request JuliaCN#152 from RexWzh/master

add solutions and edit solution 3

Author: johnnychen94

src/unresolved/101.symmetric-tree.jl renamed to src/problems/101.symmetric-tree.jl

@@ -1,8 +1,8 @@
 # ---
 # title: 101. Symmetric Tree
 # id: problem101
-# author: Tian Jun
-# date: 2020-10-31
+# author: zhwang
+# date: 2022-02-17
 # difficulty: Easy
 # categories: Tree, Depth-first Search, Breadth-first Search
 # link: <https://leetcode.com/problems/symmetric-tree/description/>
@@ -44,5 +44,13 @@
 ## @lc code=start
 using LeetCode
 
-## add your code here:
+is_symmetric_tree(root::TreeNode{Int})::Bool = is_mirror_tree(root.left, root.right)
+function is_mirror_tree(
+    t1::Union{TreeNode{Int},Nothing}, t2::Union{TreeNode{Int},Nothing}
+)::Bool
+    isnothing(t1) && isnothing(t2) && return true
+    (isnothing(t1) || isnothing(t2)) && return false
+    t1.val != t2.val && return false
+    return is_mirror_tree(t1.left, t2.right) && is_mirror_tree(t1.right, t2.left)
+end
 ## @lc code=end

src/unresolved/1020.number-of-enclaves.jl renamed to src/problems/1020.number-of-enclaves.jl

@@ -1,8 +1,8 @@
 # ---
 # title: 1020. Number of Enclaves
 # id: problem1020
-# author: Tian Jun
-# date: 2020-10-31
+# author: zhwang
+# date: 2022-02-12
 # difficulty: Medium
 # categories: Depth-first Search
 # link: <https://leetcode.com/problems/number-of-enclaves/description/>
@@ -52,5 +52,33 @@
 ## @lc code=start
 using LeetCode
 
-## add your code here:
+## BFS algorithm
+function num_of_enclaves_bfs(grid::Vector{Vector{Int}})::Int
+    m, n, queue = length(grid), length(grid[1]), Tuple{Int,Int}[]
+    (m <= 2 || n <= 2) && return 0
+    for i in 1:m ## left and right border
+        grid[i][1] == 1 && push!(queue, (i, 1))
+        grid[i][n] == 1 && push!(queue, (i, n))
+    end
+    for i in 2:(n - 1)
+        grid[1][i] == 1 && push!(queue, (1, i))
+        grid[m][i] == 1 && push!(queue, (m, i))
+    end
+    walkoff = copy(queue)
+    while length(queue) != 0
+        i, j = popfirst!(queue)
+        for (a, b) in [(i - 1, j), (i + 1, j), (i, j - 1), (i, j + 1)]
+            if a >= 1 &&
+                b >= 1 &&
+                a <= m &&
+                b <= n &&
+                grid[a][b] != 0 &&
+                !((a, b) in walkoff)
+                push!(walkoff, (a, b))
+                push!(queue, (a, b))
+            end
+        end
+    end
+    return sum(sum(line) for line in grid) - length(walkoff)
+end
 ## @lc code=end

src/unresolved/113.path-sum-ii.jl renamed to src/problems/113.path-sum-ii.jl

@@ -1,8 +1,8 @@
 # ---
 # title: 113. Path Sum II
 # id: problem113
-# author: Tian Jun
-# date: 2020-10-31
+# author: zhwang
+# date: 2022-01-23
 # difficulty: Medium
 # categories: Tree, Depth-first Search
 # link: <https://leetcode.com/problems/path-sum-ii/description/>
@@ -43,5 +43,17 @@
 ## @lc code=start
 using LeetCode
 
-## add your code here:
+function path_sum_113(node::Union{Nothing,TreeNode}, target::Int)::Vector{Vector{Int}}
+    isnothing(node) && return Vector{Vector{Int}}[]
+    isnothing(node.left) &&
+        isnothing(node.right) &&
+        return node.val != target ? Vector{Vector{Int}}[] : [[target]]
+    paths = path_sum_113(node.left, target - node.val)
+    paths = vcat(paths, path_sum_113(node.right, target - node.val))
+    for path in paths
+        pushfirst!(path, node.val)
+    end
+    return paths
+end
+
 ## @lc code=end

src/unresolved/1137.n-th-tribonacci-number.jl renamed to src/problems/1137.n-th-tribonacci-number.jl

@@ -1,8 +1,8 @@
 # ---
 # title: 1137. N-th Tribonacci Number
 # id: problem1137
-# author: Tian Jun
-# date: 2020-10-31
+# author: zhwang
+# date: 2022-02-10
 # difficulty: Easy
 # categories: Recursion
 # link: <https://leetcode.com/problems/n-th-tribonacci-number/description/>
@@ -47,5 +47,12 @@
 ## @lc code=start
 using LeetCode
 
-## add your code here:
+function tribonacci_1137(n::Int)::Int
+    n <= 1 && return n
+    a, b, c = 0, 1, 1
+    for _ in 1:(n - 2)
+        a, b, c = b, c, a + b + c
+    end
+    return c
+end
 ## @lc code=end

src/unresolved/118.pascals-triangle.jl renamed to src/problems/118.pascals-triangle.jl

@@ -1,8 +1,8 @@
 # ---
 # title: 118. Pascal's Triangle
 # id: problem118
-# author: Tian Jun
-# date: 2020-10-31
+# author: zhwang
+# date: 2022-01-17
 # difficulty: Easy
 # categories: Array
 # link: <https://leetcode.com/problems/pascals-triangle/description/>
@@ -35,5 +35,5 @@
 ## @lc code=start
 using LeetCode
 
-## add your code here:
+pascals_triangle(numRows::Int) = [[binomial(k, i) for i in 0:k] for k in 0:(numRows - 1)]
 ## @lc code=end

src/unresolved/1189.maximum-number-of-balloons.jl renamed to src/problems/1189.maximum-number-of-balloons.jl

@@ -1,8 +1,8 @@
 # ---
 # title: 1189. Maximum Number of Balloons
 # id: problem1189
-# author: Tian Jun
-# date: 2020-10-31
+# author: zhwang
+# date: 2022-02-13
 # difficulty: Easy
 # categories: Hash Table, String
 # link: <https://leetcode.com/problems/maximum-number-of-balloons/description/>
@@ -56,5 +56,13 @@
 ## @lc code=start
 using LeetCode
 
-## add your code here:
+function max_num_of_ballons(text::String)::Int
+    words = Dict{Char,Int}(s => 0 for s in "balon")
+    for s in text
+        if haskey(words, s)
+            words[s] += 1
+        end
+    end
+    return min(words['b'], words['a'], words['l'] ÷ 2, words['o'] ÷ 2, words['n'])
+end
 ## @lc code=end

src/unresolved/121.best-time-to-buy-and-sell-stock.jl renamed to src/problems/121.best-time-to-buy-and-sell-stock.jl

@@ -1,8 +1,8 @@
 # ---
 # title: 121. Best Time to Buy and Sell Stock
 # id: problem121
-# author: Tian Jun
-# date: 2020-10-31
+# author: zhwang
+# date: 2022-01-17
 # difficulty: Easy
 # categories: Array, Dynamic Programming
 # link: <https://leetcode.com/problems/best-time-to-buy-and-sell-stock/description/>
@@ -41,5 +41,13 @@
 ## @lc code=start
 using LeetCode
 
-## add your code here:
+function max_profit_121(prices::Vector{Int})::Int
+    min_cost, profit = prices[1], 0
+    for price in @view prices[2:end]
+        profit = max(profit, price - min_cost)
+        min_cost = min(min_cost, price)
+    end
+    return profit
+end
+
 ## @lc code=end

src/unresolved/1220.count-vowels-permutation.jl renamed to src/problems/1220.count-vowels-permutation.jl

@@ -1,8 +1,8 @@
 # ---
 # title: 1220. Count Vowels Permutation
 # id: problem1220
-# author: Tian Jun
-# date: 2020-10-31
+# author: zhwang
+# date: 2022-01-22
 # difficulty: Hard
 # categories: Dynamic Programming
 # link: <https://leetcode.com/problems/count-vowels-permutation/description/>
@@ -58,5 +58,20 @@
 ## @lc code=start
 using LeetCode
 
-## add your code here:
+function count_vowel_permutation(n::Int)::Int
+    table = Dict{Char,Int}(i => 1 for i in "aeiou")
+    quotient = 10^9 + 7
+    for _ in 1:(n - 1)
+        a = table['e'] + table['i'] + table['u']
+        e = table['a'] + table['i']
+        i = table['e'] + table['o']
+        o = table['i']
+        u = table['i'] + table['o']
+        table['a'], table['e'], table['i'], table['o'], table['u'] = map(
+            x -> mod(x, quotient), [a, e, i, o, u]
+        )
+    end
+    return mod(sum(values(table)), quotient)
+end
+
 ## @lc code=end

src/unresolved/1332.remove-palindromic-subsequences.jl renamed to src/problems/1332.remove-palindromic-subsequences.jl

@@ -2,7 +2,7 @@
 # title: 1332. Remove Palindromic Subsequences
 # id: problem1332
 # author: Tian Jun
-# date: 2020-10-31
+# date: 2022-01-22
 # difficulty: Easy
 # categories: String
 # link: <https://leetcode.com/problems/remove-palindromic-subsequences/description/>
@@ -70,5 +70,6 @@
 ## @lc code=start
 using LeetCode
 
-## add your code here:
+remove_palindromic_subsequences(s::String) = (s == reverse(s)) ? 1 : 2
+
 ## @lc code=end

src/unresolved/1345.jump-game-iv.jl renamed to src/problems/1345.jump-game-iv.jl

@@ -1,8 +1,8 @@
 # ---
 # title: 1345. Jump Game IV
 # id: problem1345
-# author: Tian Jun
-# date: 2020-10-31
+# author: zhwang
+# date: 2022-01-22
 # difficulty: Hard
 # categories: Breadth-first Search
 # link: <https://leetcode.com/problems/jump-game-iv/description/>
@@ -78,5 +78,35 @@
 ## @lc code=start
 using LeetCode
 
-## add your code here:
+function min_jumps_1345(arr::Vector{Int})::Int
+    ## data initialize
+    n, step = length(arr), 0
+    nums = Dict{Int,Set}(x => Set{Int}() for x in Set{Int}(arr))
+    for (i, val) in enumerate(arr)
+        push!(nums[val], i)
+    end
+    ## BFS Search
+    up_nums, up_inds, inds = Set{Int}([arr[1]]), Set{Int}([1]), Set{Int}([0, 1, n + 1])
+    while !(n in up_inds)
+        down_inds = Set{Int}()
+        ## indexs by numbers
+        for num in up_nums
+            union!(down_inds, nums[num])
+        end
+        ## nearby indexs
+        for i in up_inds
+            push!(down_inds, i - 1)
+            push!(down_inds, i + 1)
+        end
+        ## remove extra indexs
+        for i in down_inds
+            i in inds && delete!(down_inds, i)
+        end
+        up_inds, up_nums = down_inds, Set{Int}(arr[i] for i in down_inds)
+        union!(inds, up_inds)
+        step += 1
+    end
+    return step
+end
+
 ## @lc code=end

src/unresolved/136.single-number.jl renamed to src/problems/136.single-number.jl

@@ -1,8 +1,8 @@
 # ---
 # title: 136. Single Number
 # id: problem136
-# author: Tian Jun
-# date: 2020-10-31
+# author: zhwang
+# date: 2022-02-15
 # difficulty: Easy
 # categories: Hash Table, Bit Manipulation
 # link: <https://leetcode.com/problems/single-number/description/>
@@ -53,5 +53,11 @@
 ## @lc code=start
 using LeetCode
 
-## add your code here:
+function single_number_136(nums::Vector{Int})::Int
+    a = 0
+    for i in nums
+        a ⊻= i
+    end
+    return a
+end
 ## @lc code=end

src/unresolved/1380.lucky-numbers-in-a-matrix.jl renamed to src/problems/1380.lucky-numbers-in-a-matrix.jl

@@ -1,8 +1,8 @@
 # ---
 # title: 1380. Lucky Numbers in a Matrix
 # id: problem1380
-# author: Tian Jun
-# date: 2020-10-31
+# author: zhwang
+# date: 2022-02-15
 # difficulty: Easy
 # categories: Array
 # link: <https://leetcode.com/problems/lucky-numbers-in-a-matrix/description/>
@@ -56,6 +56,21 @@
 # 
 ## @lc code=start
 using LeetCode
-
-## add your code here:
+function lucky_numbers(matrix::Vector{Vector{Int}})::Vector{Int}
+    m, n = length(matrix), length(matrix[1])
+    row_min = Dict{Int,Tuple{Int,Int}}(i => (matrix[i][1], 1) for i in 1:m)
+    col_max = Dict{Int,Tuple{Int,Int}}(j => (0, 0) for j in 1:n)
+    for i in 1:m
+        for j in 1:n
+            c = matrix[i][j]
+            if c < row_min[i][1]
+                row_min[i] = (c, j)
+            end
+            if c > col_max[j][1]
+                col_max[j] = (c, i)
+            end
+        end
+    end
+    return [row_min[i][1] for i in 1:m if col_max[row_min[i][2]][2] == i]
+end
 ## @lc code=end

src/unresolved/141.linked-list-cycle.jl renamed to src/problems/141.linked-list-cycle.jl

@@ -1,8 +1,8 @@
 # ---
 # title: 141. Linked List Cycle
 # id: problem141
-# author: Tian Jun
-# date: 2020-10-31
+# author: zhwang
+# date: 2022-02-15
 # difficulty: Easy
 # categories: Linked List, Two Pointers
 # link: <https://leetcode.com/problems/linked-list-cycle/description/>
@@ -70,6 +70,13 @@
 # 
 ## @lc code=start
 using LeetCode
-
-## add your code here:
+function has_cycle(head::Union{ListNode,Nothing})::Bool
+    isnothing(head) && return false
+    swift = slow = head
+    while !isnothing(swift.next) && !isnothing(swift.next.next)
+        slow, swift = slow.next, swift.next.next
+        slow === swift && return true
+    end
+    return false
+end
 ## @lc code=end

src/unresolved/1447.simplified-fractions.jl renamed to src/problems/1447.simplified-fractions.jl

@@ -1,8 +1,8 @@
 # ---
 # title: 1447. Simplified Fractions
 # id: problem1447
-# author: Tian Jun
-# date: 2020-10-31
+# author: zhwang
+# date: 2022-02-10
 # difficulty: Medium
 # categories: Math
 # link: <https://leetcode.com/problems/simplified-fractions/description/>
@@ -57,5 +57,5 @@
 ## @lc code=start
 using LeetCode
 
-## add your code here:
+simplified_fractions(n::Int) = ["$p/$q" for q in 2:n for p in 1:(q - 1) if gcd(p, q) == 1]
 ## @lc code=end