added dutch national flag algorithm or dijkstra 3way partioning in sorts

Author: Arnav-NK

src/main/java/com/thealgorithms/sorts/DijkstraThreeWayPartition.java

@@ -0,0 +1,39 @@
+package com.thealgorithms.sorts;
+public class DijkstraThreeWayPartition {
+
+    public static void threeWayPartition(int[] arr, int pivot) {
+        int low = 0, mid = 0;
+        int high = arr.length - 1;
+        //this will sort the array in o(n) time complexity
+        //also with no extra space i,e o(1) space complexity
+        while (mid <= high) {
+            if (arr[mid] < pivot) {
+                // Swap
+                int temp = arr[low];
+                arr[low] = arr[mid];
+                arr[mid] = temp;
+
+                low++;
+                mid++;
+            } else if (arr[mid] > pivot) {
+                // Swap 
+                int temp = arr[mid];
+                arr[mid] = arr[high];
+                arr[high] = temp;
+
+                high--;
+            } else {
+                mid++;
+            }
+        }
+    }
+
+    public static void main(String[] args) {
+        int[] arr = {2, 1, 2, 3, 2, 1, 3, 2};
+        int pivot = 2;
+        threeWayPartition(arr, pivot);
+        for (int num : arr) {
+            System.out.print(num + " ");
+        }
+    }
+}