add methods to 139

Author: RexWzh

src/problems/139.word-break.jl

@@ -50,7 +50,7 @@
 using LeetCode
 
 ## BFS
-function word_break(s::String, word_dict::Vector{String})::Bool
+function word_break_bfs(s::String, word_dict::Vector{String})::Bool
     n, word_dict = length(s), sort!(word_dict; by=x -> length(x))
     valids, valid_pos = fill(false, n), [0]
     while !isempty(valid_pos)
@@ -66,4 +66,17 @@ function word_break(s::String, word_dict::Vector{String})::Bool
     end
     return false
 end
+
+## Dynamic Programming
+function word_break(s::String, word_dict::Vector{String})::Bool
+    lens = sort!(unique!(length.(word_dict)))
+    dp = append!([true], fill(false, length(s)))
+    for i in eachindex(dp)
+        for len in lens
+            i > len || break
+            dp[i - len] && s[(i - len):(i - 1)] ∈ word_dict && (dp[i] = true)
+        end
+    end
+    return last(dp)
+end
 ## @lc code=end

test/problems/139.word-break.jl

@@ -1,8 +1,14 @@
 @testset "139.word-break.jl" begin
-    @test word_break("leetcode", ["leet", "code"]) == true
-    @test word_break("catsandog", ["cats", "dog", "sand", "and", "cat"]) == false
-    @test word_break("applepenapple", ["apple", "pen"]) == true
-    @test word_break("a", ["b"]) == false
-    @test word_break("a"^150 * "b", ["a"^i for i in 1:10]) == false
-    @test word_break("bb", ["a", "b", "bbb", "bbbb"]) == true
+    tcase1 = ("leetcode", ["leet", "code"])
+    tcase2 = ("applepenapple", ["apple", "pen"])
+    tcase3 = ("bb", ["a", "b", "bbb", "bbbb"])
+    fcase1 = ("catsandog", ["cats", "dog", "sand", "and", "cat"])
+    fcase2 = ("a", ["b"])
+    fcase3 = ("a"^150 * "b", ["a"^i for i in 1:10])
+    @test word_break(tcase1...) && word_break_bfs(tcase1...)
+    @test word_break(tcase2...) && word_break_bfs(tcase2...)
+    @test word_break(tcase3...) && word_break_bfs(tcase3...)
+    @test !word_break(fcase1...) && !word_break_bfs(fcase1...)
+    @test !word_break(fcase2...) && !word_break_bfs(fcase2...)
+    @test !word_break(fcase3...) && !word_break_bfs(fcase3...)
 end