Pyramid pattern

Projects/Algorithms/Stack/nextGreaterElement.java

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+import java.util.*;
+
+public class NextGreaterElement {
+
+    /**
+     * Function to find Next Greater Element for each element in the array.
+     *
+     * @param arr Input array of integers
+     * @return Array containing next greater elements
+     */
+    public static int[] findNextGreater(int[] arr) {
+        int n = arr.length;
+        int[] result = new int[n];
+
+        // Stack to store elements
+        Stack<Integer> stack = new Stack<>();
+
+        // Traverse from right to left
+        for (int i = n - 1; i >= 0; i--) {
+
+            // Remove elements from stack that are <= current element
+            while (!stack.isEmpty() && stack.peek() <= arr[i]) {
+                stack.pop();
+            }
+
+            // If stack is empty, no greater element exists
+            if (stack.isEmpty()) {
+                result[i] = -1;
+            } else {
+                // Top of stack is the next greater element
+                result[i] = stack.peek();
+            }
+
+            // Push current element onto stack
+            stack.push(arr[i]);
+        }
+
+        return result;
+    }
+
+    /**
+     * Driver method to test the function
+     */
+    public static void main(String[] args) {
+        int[] arr = {4, 5, 2, 10, 8};
+
+        int[] result = findNextGreater(arr);
+
+        System.out.println("Next Greater Elements:");
+        for (int num : result) {
+            System.out.print(num + " ");
+        }
+    }
+}

Projects/Patterns/pyramidPattern.java

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+public class PyramidPattern {
+    public static void main(String[] args) {
+        int n = 5; // number of rows
+
+        for (int i = 1; i <= n; i++) {
+
+            // print spaces
+            for (int j = 1; j <= n - i; j++) {
+                System.out.print(" ");
+            }
+
+            // print stars
+            for (int j = 1; j <= i; j++) {
+                System.out.print("* ");
+            }
+
+            // move to next line
+            System.out.println();
+        }
+    }
+}