Maximum possible number with the given operation - GeeksforGeeks

19 Mar, 2022
Given a positive integer N, the task is to convert this integer to the maximum possible integer without leading zeroes by changing the digits. A digit X can only be changed into a digit Y if X + Y = 9.Examples:  
Input: N = 42 Output: 57 Change 4 -> 5 and 2 -> 7.Input: N = 1 Output: 8  
 
Approach: Only the digits which are greater than or equal to 5 need to be changed as changing the digits which are less than 5 will result in a larger number. After all the required digits have been updated, check whether the resultant number has a leading zero, if yes then change it to a 9.Below is the implementation of the above approach:  
C++
Java
Python3
C#
Javascript
// C++ implementation of the approach#include <bits/stdc++.h>using namespace std; // Function to return the maximum possible// integer that can be obtained from the// given integer after performing// the given operationsstring maxInt(string str){    // For every digit    for (int i = 0; i < str.length(); i++) {         // Digits greater than or equal to 5        // need not to be changed as changing        // them will lead to a smaller number        if (str[i] < '5') {            str[i] = ('9' - str[i]) + '0';        }    }     // The resulting integer    // cannot have leading zero    if (str[0] == '0')        str[0] = '9';     return str;} // Driver codeint main(){    string str = "42";     cout << maxInt(str);     return 0;}
// Java implementation of the approachclass GFG{     // Function to return the maximum possible    // integer that can be obtained from the    // given integer after performing    // the given operations    static String maxInt(char str[])    {        // For every digit        for (int i = 0; i < str.length; i++)        {                 // Digits greater than or equal to 5            // need not to be changed as changing            // them will lead to a smaller number            if (str[i] < '5')            {                str[i] = (char)(('9' - str[i]) + '0');            }        }             // The resulting integer        // cannot have leading zero        if (str[0] == '0')            str[0] = '9';             String str2 = new String(str);        return str2;    }         // Driver code    public static void main (String[] args)    {        String str = "42";             System.out.println(maxInt(str.toCharArray()));    }} // This code is contributed by AnkitRai01
# Python3 implementation of the approach # Function to return the maximum possible# integer that can be obtained from the# given integer after performing# the given operationsdef maxInt(string):    string2 = ""         # For every digit    for i in range(0, len(string)):         # Digits greater than or equal to 5        # need not to be changed as changing        # them will lead to a smaller number        if (string[i] < '5'):            string2 += str((ord('9') - ord(string[i])))        else:            string2 += str(string[i])                 # The resulting integer    # cannot have leading zero    if (string2[0] == '0'):        string2[0] = '9'     return string2 # Driver codeif __name__ == '__main__':     string = "42"    print(maxInt(string)) # This code is contributed by ashutosh450
// C# implementation of the approachusing System; class GFG{     // Function to return the maximum possible    // integer that can be obtained from the    // given integer after performing    // the given operations    static String maxInt(char []str)    {        // For every digit        for (int i = 0; i < str.Length; i++)        {                 // Digits greater than or equal to 5            // need not to be changed as changing            // them will lead to a smaller number            if (str[i] < '5')            {                str[i] = (char)(('9' - str[i]) + '0');            }        }             // The resulting integer        // cannot have leading zero        if (str[0] == '0')            str[0] = '9';             String str2 = new String(str);        return str2;    }         // Driver code    public static void Main (String []args)    {        String str = "42";             Console.WriteLine(maxInt(str.ToCharArray()));    }} // This code is contributed by Arnab Kundu
<script>// Javascript implementation of the// above approach // Function to return the maximum possible// integer that can be obtained from the// given integer after performing// the given operationsfunction maxInt(str){    // For every digit    var str2 = "";    for (var i = 0; i < str.length; i++) {           // Digits greater than or equal to 5        // need not to be changed as changing        // them will lead to a smaller number        if (str[i] < '5') {            var l = ('9'.charCodeAt(0) - str[i].charCodeAt(0)) + '0'.charCodeAt(0);            str2 = str2.concat(String.fromCharCode(l));        }    }       // The resulting integer    // cannot have leading zero    if (str2[0] == '0')        str2[0] = '9';       return str2;} // Driver codevar str = "42";document.write(maxInt(str)) // This code is contributed by ShubhamSingh10</script>
57
 
Time Complexity: O(|str|)
Auxiliary Space: O(1)
ashutosh450
ankthon
andrew1234
SHUBHAMSINGH10
sweetyty
subham348
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