Added solution for firstMissingPositive in python and Updated README.md file

Author: samir-0711

README.md

@@ -378,7 +378,7 @@ LeetCode
 |44|[Wildcard Matching](https://leetcode.com/problems/wildcard-matching/)| [C++](./algorithms/cpp/wildcardMatching/wildcardMatching.cpp)|Hard|
 |43|[Multiply Strings](https://leetcode.com/problems/multiply-strings/)| [C++](./algorithms/cpp/multiplyStrings/multiplyStrings.cpp)|Medium|
 |42|[Trapping Rain Water](https://leetcode.com/problems/trapping-rain-water/)| [C++](./algorithms/cpp/trappingRainWater/trappingRainWater.cpp)|Hard|
-|41|[First Missing Positive](https://leetcode.com/problems/first-missing-positive/)| [C++](./algorithms/cpp/firstMissingPositive/firstMissingPositive.cpp)|Hard|
+|41|[First Missing Positive](https://leetcode.com/problems/first-missing-positive/)| [C++](./algorithms/cpp/firstMissingPositive/firstMissingPositive.cpp), [Python](././algorithms/python/firstMissingPositive/firstMissingPositive.py)|Hard|
 |40|[Combination Sum II](https://leetcode.com/problems/combination-sum-ii/)| [C++](./algorithms/cpp/combinationSum/combinationSum.II.cpp)|Medium|
 |39|[Combination Sum](https://leetcode.com/problems/combination-sum/)| [C++](./algorithms/cpp/combinationSum/combinationSum.cpp)|Medium|
 |38|[Count and Say](https://leetcode.com/problems/count-and-say/)| [C++](./algorithms/cpp/countAndSay/countAndSay.cpp), [Java](./algorithms/java/src/countAndSay/CountAndSay.java)|Easy|

algorithms/python/firstMissingPositive/firstMissingPositive.py

@@ -0,0 +1,30 @@
+# question : https://leetcode.com/problems/first-missing-positive/
+# Author : Samir Rajesh Prajapati
+# Date : 2020-10-01
+
+# ********************************************************************************* 
+# * 
+# * Given an unsorted integer array, find the first missing positive integer.
+# * 
+# * For example,
+# * Given [1,2,0] return 3,
+# * and [3,4,-1,1] return 2.
+# * 
+# * Your algorithm should run in O(n) time and uses constant space.
+# * 
+# *               
+# **********************************************************************************
+
+class Solution:
+    def firstMissingPositive(self, nums: [int]) -> int:
+        for i in range(len(nums)):
+            while nums[i]>0 and nums[i]<len(nums) and nums[i]-1!=i and nums[i]!=nums[nums[i]-1]:
+                nums[nums[i]-1], nums[i] = nums[i], nums[nums[i]-1]
+        for i in range(len(nums)):
+            if i + 1 != nums[i]:
+                return i + 1 
+        return len(nums) + 1
+                
+if __name__ == '__main__':
+    number = Solution()
+    print(number.firstMissingPositive([3,4,-1,1]))