【Arai60】60問目 6. Zigzag Conversion

arai60/54-60_others/60_6_Zigzag Conversion/level_1.py

@@ -0,0 +1,20 @@
+# 各行の文字列をリストに格納して、最後に結合する。
+class Solution:
+    def convert(self, s: str, numRows: int) -> str:
+        if numRows == 1:
+            return s
+        rows = [[] for _ in range(numRows)]
+        num_row = 0
+        direction = 1
+        for c in s:
+            rows[num_row].append(c)
+            if num_row == 0:  # 0行目で折り返し
+                direction = 1
+            if num_row == numRows - 1:  # 最終行で折り返し
+                direction = -1
+            num_row += direction
+        merged_all_rows = []
+        for row in rows:
+            merged_all_rows.extend(row)
+        zigzag_string = "".join(merged_all_rows)
+        return zigzag_string

arai60/54-60_others/60_6_Zigzag Conversion/level_2.py

@@ -0,0 +1,26 @@
+# 何行目になるかは規則性があるので計算で求められる
+# 2*n-2個周期で行が繰り返される
+# 0     6
+# 1   5 7
+# 2 4   8
+# 3
+class Solution:
+    def convert(self, s: str, numRows: int) -> str:
+        if numRows == 1:
+            return s
+        rows = [[] for _ in range(numRows)]
+        cycle = 2 * numRows - 2
+        for i in range(len(s)):
+            pos = i % (cycle)
+            if pos < numRows:  # 下りのとき
+                num_row = pos
+            else:  # 上りのとき
+                # [最下行] - [折り返して何個目か]
+                # (numRows - 1) - (pos - (numRows - 1))
+                num_row = 2 * numRows - pos - 2
+            rows[num_row].append(s[i])
+        marged_all_rows = []
+        for row in rows:
+            marged_all_rows.extend(row)
+        zigzag_string = "".join(marged_all_rows)
+        return zigzag_string

arai60/54-60_others/60_6_Zigzag Conversion/level_3.py

@@ -0,0 +1,18 @@
+class Solution:
+    def convert(self, s: str, numRows: int) -> str:
+        if numRows == 1:
+            return s
+        rows = [[] for _ in range(numRows)]
+        num_row = 0
+        direction = 1
+        for c in s:
+            rows[num_row].append(c)
+            if num_row == 0:
+                direction = 1
+            if num_row == numRows - 1:
+                direction = -1
+            num_row += direction
+        merged_all_rows = []
+        for row in rows:
+            merged_all_rows.extend(row)
+        return "".join(merged_all_rows)

arai60/54-60_others/60_6_Zigzag Conversion/level_4.py

@@ -0,0 +1,15 @@
+class Solution:
+    def convert(self, s: str, numRows: int) -> str:
+        if numRows == 1:
+            return s
+        rows = [[] for _ in range(numRows)]
+        rows_index = 0
+        direction = 1
+        for c in s:
+            rows[rows_index].append(c)
+            if rows_index == 0:
+                direction = 1
+            if rows_index == numRows - 1:
+                direction = -1
+            rows_index += direction
+        return "".join(c for row in rows for c in row)