Update README.md

Author: Lokesh598

README.md

@@ -1,5 +1,16 @@
 # data-structures-and-algorithm
 
+Constraints -
+Input | Worst Time Complexity
+n ≤ 12 | O(n!)
+n ≤ 25 | O(2^n)
+n ≤ 100 | O(n^4)
+n ≤ 500 | O(n^3)
+n ≤ 10^4 | O(n^2)
+n ≤ 10^6 | O(n log n)
+n ≤ 10^8 | O(n)
+n > 10^8 | O(log n) or O(1)
+
 ## List of standard question
 
  - ## Array