diff --git a/core-java-arrays/src/main/java/com/baeldung/array/looping/LoopDiagonally.java b/core-java-arrays/src/main/java/com/baeldung/array/looping/LoopDiagonally.java new file mode 100644 index 0000000000..71e2840f45 --- /dev/null +++ b/core-java-arrays/src/main/java/com/baeldung/array/looping/LoopDiagonally.java @@ -0,0 +1,45 @@ +package com.baeldung.array.looping; + +public class LoopDiagonally { + + + public String loopDiagonally(String[][] twoDArray) { + + int length = twoDArray.length; + int diagonalLines = (length + length) - 1; + int itemsInDiagonal = 0; + int midPoint = (diagonalLines / 2) + 1; + StringBuilder output = new StringBuilder(); + + for (int i = 1; i <= diagonalLines; i++) { + + StringBuilder items = new StringBuilder(); + int rowIndex; + int columnIndex; + + if (i <= midPoint) { + itemsInDiagonal++; + for (int j = 0; j < itemsInDiagonal; j++) { + rowIndex = (i - j) - 1; + columnIndex = j; + items.append(twoDArray[rowIndex][columnIndex]); + } + } else { + itemsInDiagonal--; + for (int j = 0; j < itemsInDiagonal; j++) { + rowIndex = (length - 1) - j; + columnIndex = (i - length) + j; + items.append(twoDArray[rowIndex][columnIndex]); + } + } + + if (i != diagonalLines) { + output.append(items).append(" "); + } else { + output.append(items); + } + } + + return output.toString(); + } +} diff --git a/core-java-arrays/src/test/java/com/baeldung/array/looping/LoopDiagonallyTest.java b/core-java-arrays/src/test/java/com/baeldung/array/looping/LoopDiagonallyTest.java new file mode 100644 index 0000000000..df6079270b --- /dev/null +++ b/core-java-arrays/src/test/java/com/baeldung/array/looping/LoopDiagonallyTest.java @@ -0,0 +1,20 @@ +package com.baeldung.array.looping; + +import org.junit.Test; + +import static org.junit.Assert.assertEquals; + +public class LoopDiagonallyTest { + + @Test + public void twoArrayIsLoopedDiagonallyAsExpected() { + + LoopDiagonally loopDiagonally = new LoopDiagonally(); + String[][] twoDArray = {{"a", "b", "c"}, + {"d", "e", "f"}, + {"g", "h", "i"}}; + + String output = loopDiagonally.loopDiagonally(twoDArray); + assertEquals("a db gec hf i", output); + } +} \ No newline at end of file