diff --git a/src/main/java/com/thealgorithms/maths/PascalTriangle.java b/src/main/java/com/thealgorithms/maths/PascalTriangle.java new file mode 100644 index 000000000000..62ee3bc9aa19 --- /dev/null +++ b/src/main/java/com/thealgorithms/maths/PascalTriangle.java @@ -0,0 +1,65 @@ +package com.thealgorithms.maths; + +import java.util.Scanner; +public class PascalTriangle { + /** + *In mathematics, Pascal's triangle is a triangular array of the binomial coefficients that arises + * in probability theory, combinatorics, and algebra. In much of the Western world, it is named after + * the French mathematician Blaise Pascal, although other mathematicians studied it centuries before + * him in India, Persia, China, Germany, and Italy. + * + * The rows of Pascal's triangle are conventionally enumerated starting with row n=0 at the top (the 0th row). + * The entries in each row are numbered from the left beginning with k=0 and are usually staggered relative + * to the numbers in the adjacent rows. The triangle may be constructed in the following manner: + * In row 0 (the topmost row), there is a unique nonzero entry 1. Each entry of each subsequent row is + * constructed by adding the number above and to the left with the number above and to the right, treating + * blank entries as 0. For example, the initial number in the first (or any other) row is 1 (the sum of 0 and 1), + * whereas the numbers 1 and 3 in the third row are added to produce the number 4 in the fourth row. * + * + *

+ * link:-https://en.wikipedia.org/wiki/Pascal%27s_triangle + * + *

+ * Example:- + * 1 + * 1 1 + * 1 2 1 + * 1 3 3 1 + * 1 4 6 4 1 + * 1 5 10 10 5 1 + * 1 6 15 20 15 6 1 + * 1 7 21 35 35 21 7 1 + * 1 8 28 56 70 56 28 8 1 + * + */ + + public static int[][] pascal(int n) + { + /** + * @param arr An auxiliary array to store generated pascal triangle values + * @return + */ + int[][] arr = new int[n][n]; + /** + * @param line Iterate through every line and print integer(s) in it + * @param i Represents the column number of the element we are currently on + */ + for (int line = 0; line < n; line++) + { + /** + * @Every line has number of integers equal to line number + */ + for (int i = 0; i <= line; i++) + { + // First and last values in every row are 1 + if (line == i || i == 0) + arr[line][i] = 1; + // The rest elements are sum of values just above and left of above + else + arr[line][i] = arr[line-1][i-1] + arr[line-1][i]; + } + } + + return arr; + } +} diff --git a/src/test/java/com/thealgorithms/maths/PascalTriangleTest.java b/src/test/java/com/thealgorithms/maths/PascalTriangleTest.java new file mode 100644 index 000000000000..93c87bd25926 --- /dev/null +++ b/src/test/java/com/thealgorithms/maths/PascalTriangleTest.java @@ -0,0 +1,42 @@ + +package com.thealgorithms.maths; + +import org.junit.jupiter.api.Test; + +import static org.junit.jupiter.api.Assertions.*; + +class PascalTriangleTest { + + @Test + void testForOne() + { + int[][] result = PascalTriangle.pascal(1); + int[][] expected = {{1}}; + assertArrayEquals(result,expected); + } + + @Test + void testForTwo() + { + int[][] result = PascalTriangle.pascal(2); + int[][] expected = {{1,0},{1,1}}; + assertArrayEquals(result,expected); + } + + @Test + void testForFive() + { + int[][] result = PascalTriangle.pascal(5); + int[][] expected = {{1,0,0,0,0},{1,1,0,0,0},{1,2,1,0,0},{1,3,3,1,0},{1,4,6,4,1}}; + assertArrayEquals(result,expected); + } + + @Test + void testForEight() { + int[][] result = PascalTriangle.pascal(8); + int[][] expected = {{1,0,0,0,0,0,0,0},{1,1,0,0,0,0,0,0},{1,2,1,0,0,0,0,0},{1,3,3,1,0,0,0,0},{1,4,6,4,1,0,0,0},{1,5,10,10,5,1,0,0},{1,6,15,20,15,6,1,0},{1,7,21,35,35,21,7,1}}; + assertArrayEquals(expected, result); + } + + +} diff --git a/src/test/java/com/thealgorithms/others/ArrayLeftRotationTest.java b/src/test/java/com/thealgorithms/others/ArrayLeftRotationTest.java index 2efebb08f2ba..773a5aabf5dc 100644 --- a/src/test/java/com/thealgorithms/others/ArrayLeftRotationTest.java +++ b/src/test/java/com/thealgorithms/others/ArrayLeftRotationTest.java @@ -12,21 +12,21 @@ void testForOneElement() { int[] result = ArrayLeftRotation.rotateLeft(arr, 3); assertArrayEquals(arr, result); } - + @Test void testForZeroStep() { int[] arr = {3, 1, 5, 8, 6}; int[] result = ArrayLeftRotation.rotateLeft(arr, 0); assertArrayEquals(arr, result); } - + @Test void testForEqualSizeStep() { int[] arr = {3, 1, 5, 8, 6}; int[] result = ArrayLeftRotation.rotateLeft(arr, 5); assertArrayEquals(arr, result); } - + @Test void testForLowerSizeStep() { int[] arr = {3, 1, 5, 8, 6}; @@ -35,7 +35,7 @@ void testForLowerSizeStep() { int[] result = ArrayLeftRotation.rotateLeft(arr, n); assertArrayEquals(expected, result); } - + @Test void testForHigherSizeStep() { int[] arr = {3, 1, 5, 8, 6}; @@ -45,4 +45,4 @@ void testForHigherSizeStep() { assertArrayEquals(expected, result); } -} +} \ No newline at end of file pFad - Phonifier reborn

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