# Print the largest integer formed by inserting digit X in given string

Given a string **S **of size** N** representing a large integer value, and a positive digit **X**, the task is to print the largest integer formed by inserting the digit **X** in the string **S**.

**Examples:**

Input:S = “99”, X = 9Output:999Explanation:

The largest number that can be formed is 999 after inserting 9 into “99”.

Input:S = “-13”, X = 2Output:-123Explanation:

The largest number that can be formed is -123 after inserting 2 into “-13”.

**Approach: **The problem can be solved by iterating over the character of the string **S**. Follow the steps below to solve this problem:

- If the number
**S**is positive, then perform the following steps:- Iterate in the range
**[0, N-1]**using the variable**i**and perform the following steps**:**- If
**S[i]**is less than**X**then insert the digit**X**before**S[i]**and**break**the loop**.**

- If
- If none of the above cases satisfy, then append the digit
**X**at the end of the string**S**.

- Iterate in the range
- Else, if the number
**S**is negative, then perform the following steps:- Iterate in the range
**[0, N-1]**in using the variable**i**and perform the following steps:- If
**S[i]**is less than**X**, then insert the digit**X**before**S[i]**and**break**the loop.

- If
- If none of the above cases satisfy, then append the digit
**X**at the end of the string**S**.

- Iterate in the range
- Finally, print the largest possible string, represented by
**S**.

Below is the implementation of the above approach:

## Python3

`# Python program for the above approach` ` ` `# Function to find Largest Number after` `# insertion of a digit` `def` `largestValue(S, X):` ` ` ` ` `# If S is negative` ` ` `if` `S[` `0` `] ` `=` `=` `'-'` `:` ` ` `f ` `=` `0` ` ` `# Iterate through characters of S` ` ` `for` `i, val ` `in` `enumerate` `(S):` ` ` `if` `i ` `=` `=` `0` `:` ` ` `continue` ` ` ` ` `# If digit x is less` ` ` `# than S[i] insert digit` ` ` `# after X` ` ` `if` `X < ` `int` `(val):` ` ` `f ` `=` `1` ` ` `S ` `=` `S[:i] ` `+` `str` `(X) ` `+` `S[i:]` ` ` `break` ` ` ` ` `if` `f ` `=` `=` `0` `:` ` ` `S ` `=` `S ` `+` `str` `(X)` ` ` ` ` `# If S is positive` ` ` `else` `:` ` ` `f ` `=` `0` ` ` ` ` `# If x > S[i] insert x` ` ` `for` `i, val ` `in` `enumerate` `(S):` ` ` `if` `X > ` `int` `(val):` ` ` `f ` `=` `1` ` ` `S ` `=` `S[:i] ` `+` `str` `(X) ` `+` `S[i:]` ` ` `break` ` ` ` ` `if` `f ` `=` `=` `0` `:` ` ` `S ` `=` `S ` `+` `str` `(X)` ` ` ` ` `# Return the answer` ` ` `return` `S` ` ` ` ` `# Driver Code` ` ` `# Given Input` `S ` `=` `"-13"` `X ` `=` `2` ` ` `# Funtion Call` `print` `(largestValue(S, X))` |

**Output**

-123

**Time Complexity: **O(N)**Auxiliary Space: **O(1)

Attention reader! Don’t stop learning now. Get hold of all the important mathematical concepts for competitive programming with the **Essential Maths for CP Course** at a student-friendly price. To complete your preparation from learning a language to DS Algo and many more, please refer **Complete Interview Preparation Course****.**