added question and solution on floor of a number in sorted array

Task 1/Floor of A Number In Sorted Array/question.md

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+Find the floor of a number in a sorted array .

Task 1/Floor of A Number In Sorted Array/solution.java

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+public class FloorOfANumber {
+
+    public static void main(String[] args) {
+        int[] arr = {9, 11, 19, 22,23,24};
+        int target = 20;
+        int ans = floor(arr, target);
+        System.out.println(ans);
+    }
+
+    static int floor(int[] arr, int target) {
+        int start = 0;
+        int end = arr.length - 1;
+
+        while(start <= end) {
+            // finding the middle element
+            int mid = (start + end) / 2;
+            if (target < arr[mid]) {
+                end = mid - 1;
+            } else if (target > arr[mid]) {
+                start = mid + 1;
+            } else {
+                // ans is found
+                return mid;
+            }
+        }
+        return end;
+    }
+}