Program to find first positive missing integer in range in Python

Suppose we have a list of sorted list of distinct integers of size n, we have to find the first positive number in range [1 to n+1] that is not present in the array.

So, if the input is like nums = [0,5,1], then the output will be 2, as 2 is the first missing number in range 1 to 5.

To solve this, we will follow these steps −

• target := 1

• for each i in arr, do

  • if i is same as target, then

    • target := target + 1

• return target

Let us see the following implementation to get better understanding −

Example

 Live Demo

class Solution:
   def solve(self, arr):
      target = 1
      for i in arr:
         if i == target:
            target += 1
         return target
ob = Solution()
nums = [0,5,1]
print(ob.solve(nums))

Input

[0,5,1]

Output

2

Arnab Chakraborty

Updated on 08-Oct-2020 10:28:27

• Related Questions & Answers
• First Missing Positive in Python
• Program to find kth missing positive number in an array in Python
• Program to find lowest possible integer that is missing in the array in Python
• Find missing numbers in a sorted list range in Python
• Python program to reverse bits of a positive integer number?
• Find missing elements of a range in C++
• Find the one missing number in range using C++
• Program to express a positive integer number in words in C++
• Print first k digits of 1/n where n is a positive integer in C Program
• Find Positive Integer Solution for a Given Equation in C++
• Write a program in C++ to find the missing positive number in a given array of unsorted integers
• Write a program in Java to find the missing positive number in a given array of unsorted integers
• Python program to find missing and additional values in two lists?
• Add a positive integer constraint to an integer column in MySQL?
• Maximum positive integer divisible by C and is in the range [A, B] in C++