diff --git a/arai60/zigzag_conversion/phase1.py b/arai60/zigzag_conversion/phase1.py
new file mode 100644
index 0000000..c1e1323
--- /dev/null
+++ b/arai60/zigzag_conversion/phase1.py
@@ -0,0 +1,25 @@
+def create_string_index_to_store_index(numRows: int)->dict:
+    string_index_to_store_index = {}
+    for index in range(numRows):
+        string_index_to_store_index[index] = index
+        #{0: 0, 1: 1, 2: 2, ..., numRows - 1: numRows - 1}
+    for index in range(numRows-2):
+        string_index_to_store_index[index + numRows] = numRows - index - 2
+    # 周期2*numRows - 2で変化するindexの辞書ができた
+    return string_index_to_store_index
+
+def string_index(index, numRows):
+    if numRows == 1:
+        return 0
+    return index % (2 * numRows - 2)
+
+class Solution:
+    def convert(self, s: str, numRows: int) -> str:
+        concat_strings = ["" for _ in range(numRows)]
+        string_index_to_store_index = create_string_index_to_store_index(numRows)
+        for index, string in enumerate(s):
+            concat_strings[string_index_to_store_index[string_index(index, numRows)]] += string
+        concated_string = ""
+        for string in concat_strings:
+            concated_string += string
+        return concated_string
\ No newline at end of file
diff --git a/arai60/zigzag_conversion/phase2.py b/arai60/zigzag_conversion/phase2.py
new file mode 100644
index 0000000..532e6fe
--- /dev/null
+++ b/arai60/zigzag_conversion/phase2.py
@@ -0,0 +1,36 @@
+# discordで他の人の回答も見てみた。
+# 結構な人が文字列をガチャガチャしていていた
+# https://github.com/nittoco/leetcode/pull/4/files, https://github.com/hayashi-ay/leetcode/pull/71/files
+# 僕も最初思いついた解法は, 1行目は周期ずつ文字列を飛ばす, 2行目は周期ずつ文字列を飛ばし, 
+# 何個か戻ったところに文字があるのでそれを回収してくる...のような方法でいこうとしたが, 頭がこんがらがってしまい, 他にいい方法がないかを考えてみた。
+# i行目にある文字は表現するためには, 文字列のj-index番目とnumRowsに関する何らかの余りで表現できることに気づいたので, それを用いた。
+
+def create_string_index_to_column_index(numRows: int)->dict:
+    string_index_to_column_index = {}
+    for string_index in range(numRows):
+        column_index = string_index
+        string_index_to_column_index[string_index] = column_index
+        #{0: 0, 1: 1, 2: 2, ..., numRows - 1: numRows - 1}
+    for difference_index in range(numRows - 2):
+        string_index = numRows + difference_index
+        column_index = numRows - difference_index - 2
+        string_index_to_column_index[string_index] = column_index
+    # 周期2*numRows - 2で変化するindexの辞書ができた
+    #{0: 0, 1: 1, 2: 2, ..., numRows - 1: numRows - 1, numRows: numRows - 2, ..., 2 * numRows - 3: 1}
+    return string_index_to_column_index
+
+def create_remain_string_index(index, numRows):
+    if numRows == 1:
+        return 0
+    return index % (2 * numRows - 2)
+
+class Solution:
+    def convert(self, s: str, numRows: int) -> str:
+        concat_strings = ["" for _ in range(numRows)]
+        string_index_to_column_index = create_string_index_to_column_index(numRows)
+        for string_index, string in enumerate(s):
+            concat_strings[string_index_to_column_index[create_remain_string_index(string_index, numRows)]] += string
+        concated_string = ""
+        for string in concat_strings:
+            concated_string += string
+        return concated_string
\ No newline at end of file
diff --git a/arai60/zigzag_conversion/phase3.py b/arai60/zigzag_conversion/phase3.py
new file mode 100644
index 0000000..6870285
--- /dev/null
+++ b/arai60/zigzag_conversion/phase3.py
@@ -0,0 +1,28 @@
+def create_string_index_to_column_index(numRows: int)->dict:
+    string_index_to_column_index = {}
+    for string_index in range(numRows):
+        column_index = string_index 
+        string_index_to_column_index[string_index] = column_index
+    for difference_index in range(numRows-2):
+        string_index = numRows + difference_index
+        column_index = numRows - difference_index - 2
+        string_index_to_column_index[string_index] = column_index
+    # return dict: {0:0, 1:1, ..., numRows-1: numRows-1, numRows: numRows-2, ..., 2*numRows-3:1}
+    return string_index_to_column_index
+
+def create_remain_string_index(string_index, numRows):
+    if numRows == 1:
+        return 0
+    return string_index % (2 * numRows - 2)
+
+class Solution:
+    def convert(self, s: str, numRows: int) -> str:
+        concat_strings = ["" for _ in range(numRows)] #Store the strings of each column
+        string_index_to_column_index = create_string_index_to_column_index(numRows) #dict: string_index->column_index
+        for string_index, string in enumerate(s):
+            column_index = string_index_to_column_index[create_remain_string_index(string_index, numRows)]
+            concat_strings[column_index] += string
+        concated_string = ""
+        for string in concat_strings:
+            concated_string += string
+        return concated_string
\ No newline at end of file
diff --git a/arai60/zigzag_conversion/phase4.py b/arai60/zigzag_conversion/phase4.py
new file mode 100644
index 0000000..42bdf03
--- /dev/null
+++ b/arai60/zigzag_conversion/phase4.py
@@ -0,0 +1,30 @@
+"""
+Reference
+shining-ai san: https://github.com/shining-ai/leetcode/pull/60/files
+周期を考えて, 何番目のrowにいれるかという解法をstep1-3から書いてきたが, 
+shining-aiのコードを見てrowの移動方向を変える方が頭のリソースの節約にも, 
+空間計算量の節約にもつながることに気づいたので使ってみます
+
+
+"""
+
+class Solution:
+    def convert(self, s: str, numRows: int) -> str:
+        if numRows == 1:
+            return s
+
+        row_strings = [[] for _ in range(numRows)]
+        
+        direction = 1
+        row_index = 0
+        for c in s:
+            row_strings[row_index].append(c)
+
+            if row_index == 0:
+                direction = 1
+            elif row_index == numRows - 1:
+                direction = -1
+            
+            row_index += direction
+        
+        return "".join(row_char for row_string in row_strings for row_char in row_string)
\ No newline at end of file