[LeetCode]Zigzag_conversion

Author: WongueShin

LeetCode/Array/zigzag_conversion/wongue_shin.dart

@@ -0,0 +1,56 @@
+/*
+Runtime 380 ms
+Beats 94.83%
+--------------
+Memory 160.4 MB
+Beats 43.10%
+ */
+
+// import 'package:flutter_test/flutter_test.dart';
+
+class Solution {
+  late final int _sliceLen;
+
+  String convert(String s, int numRows) {
+    // numRows 가 1인경우, 원본 스트링을 그대로 반환하면 된다.
+    if (numRows == 1) return s;
+    _sliceLen = numRows + (numRows - 2);
+    List<List<String>> ans = List.generate(numRows, (index) => []);
+    for (int i = 0; i < s.length; i = i + _sliceLen) {
+      int endIdx = i + _sliceLen < s.length ? i + _sliceLen : s.length;
+      _reorderString(ans, s.substring(i, endIdx), numRows);
+    }
+
+    return ans.map((e) => e.join()).join();
+  }
+
+  void _reorderString(List<List<String>> ans, String slicedString, int numRows) {
+    for (int idx = 0; idx < slicedString.length; idx++) {
+      if (idx == 0 || idx == numRows - 1 || idx < numRows) {
+        ans[idx].add(slicedString[idx]);
+        continue;
+      }
+      ans[_sliceLen - idx].add(slicedString[idx]);
+    }
+  }
+}
+
+/*
+TEST_CODE
+--------
+void main() {
+  group(
+    "Zigzag Conversion",
+        () {
+      late Solution solution;
+      setUp(() {
+        solution = Solution();
+      });
+
+      test('case01', () => expect(solution.convert("PAYPALISHIRING", 3), equals("PAHNAPLSIIGYIR")));
+      test('case02', () => expect(solution.convert("PAYPALISHIRING", 4), equals("PINALSIGYAHRPI")));
+      test('case03', () => expect(solution.convert("A", 1), equals("A")));
+    },
+  );
+}
+*/