Added task 2075.

Author: javadev

src/main/java/g2001_2100/s2075_decode_the_slanted_ciphertext/Solution.java

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+package g2001_2100.s2075_decode_the_slanted_ciphertext;
+
+// #Medium #String #Simulation #2022_05_29_Time_48_ms_(68.23%)_Space_77.9_MB_(64.71%)
+
+public class Solution {
+    public String decodeCiphertext(String encodedText, int rows) {
+        if (rows == 1) {
+            return encodedText;
+        }
+        int total = encodedText.length();
+        int cols = total / rows;
+        char[][] grid = new char[rows][cols];
+        int index = 0;
+        for (int i = 0; i < rows; i++) {
+            for (int j = 0; j < cols; j++) {
+                grid[i][j] = encodedText.charAt(index++);
+            }
+        }
+        StringBuilder sb = new StringBuilder();
+        int colIndex = 0;
+        while (colIndex < cols) {
+            for (int j = colIndex, i = 0; j < cols && i < rows; j++, i++) {
+                sb.append(grid[i][j]);
+            }
+            colIndex++;
+        }
+        int i = sb.length() - 1;
+        while (i >= 0 && sb.charAt(i) == ' ') {
+            i--;
+        }
+        return sb.substring(0, i + 1);
+    }
+}

src/main/java/g2001_2100/s2075_decode_the_slanted_ciphertext/readme.md

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+2075\. Decode the Slanted Ciphertext
+
+Medium
+
+A string `originalText` is encoded using a **slanted transposition cipher** to a string `encodedText` with the help of a matrix having a **fixed number of rows** `rows`.
+
+`originalText` is placed first in a top-left to bottom-right manner.
+
+![](https://assets.leetcode.com/uploads/2021/11/07/exa11.png)
+
+The blue cells are filled first, followed by the red cells, then the yellow cells, and so on, until we reach the end of `originalText`. The arrow indicates the order in which the cells are filled. All empty cells are filled with `' '`. The number of columns is chosen such that the rightmost column will **not be empty** after filling in `originalText`.
+
+`encodedText` is then formed by appending all characters of the matrix in a row-wise fashion.
+
+![](https://assets.leetcode.com/uploads/2021/11/07/exa12.png)
+
+The characters in the blue cells are appended first to `encodedText`, then the red cells, and so on, and finally the yellow cells. The arrow indicates the order in which the cells are accessed.
+
+For example, if `originalText = "cipher"` and `rows = 3`, then we encode it in the following manner:
+
+![](https://assets.leetcode.com/uploads/2021/10/25/desc2.png)
+
+The blue arrows depict how `originalText` is placed in the matrix, and the red arrows denote the order in which `encodedText` is formed. In the above example, `encodedText = "ch ie pr"`.
+
+Given the encoded string `encodedText` and number of rows `rows`, return _the original string_ `originalText`.
+
+**Note:** `originalText` **does not** have any trailing spaces `' '`. The test cases are generated such that there is only one possible `originalText`.
+
+**Example 1:**
+
+**Input:** encodedText = "ch ie pr", rows = 3
+
+**Output:** "cipher"
+
+**Explanation:** This is the same example described in the problem description. 
+
+**Example 2:**
+
+![](https://assets.leetcode.com/uploads/2021/10/26/exam1.png)
+
+**Input:** encodedText = "iveo eed l te olc", rows = 4
+
+**Output:** "i love leetcode"
+
+**Explanation:** The figure above denotes the matrix that was used to encode originalText.
+
+The blue arrows show how we can find originalText from encodedText. 
+
+**Example 3:**
+
+![](https://assets.leetcode.com/uploads/2021/10/26/eg2.png)
+
+**Input:** encodedText = "coding", rows = 1
+
+**Output:** "coding"
+
+**Explanation:** Since there is only 1 row, both originalText and encodedText are the same. 
+
+**Constraints:**
+
+*   <code>0 <= encodedText.length <= 10<sup>6</sup></code>
+*   `encodedText` consists of lowercase English letters and `' '` only.
+*   `encodedText` is a valid encoding of some `originalText` that **does not** have trailing spaces.
+*   `1 <= rows <= 1000`
+*   The testcases are generated such that there is **only one** possible `originalText`.

src/test/java/g2001_2100/s2075_decode_the_slanted_ciphertext/SolutionTest.java

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+package g2001_2100.s2075_decode_the_slanted_ciphertext;
+
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.hamcrest.MatcherAssert.assertThat;
+
+import org.junit.jupiter.api.Test;
+
+class SolutionTest {
+    @Test
+    void decodeCiphertext() {
+        assertThat(new Solution().decodeCiphertext("ch   ie   pr", 3), equalTo("cipher"));
+    }
+
+    @Test
+    void decodeCiphertext2() {
+        assertThat(
+                new Solution().decodeCiphertext("iveo    eed   l te   olc", 4),
+                equalTo("i love leetcode"));
+    }
+
+    @Test
+    void decodeCiphertext3() {
+        assertThat(new Solution().decodeCiphertext("coding", 1), equalTo("coding"));
+    }
+}