Extract maximum numeric value from a given string.md

Given a alphanumeric string S, extract maximum numeric value from S. Input: S = 100klh564abc365bg Output: 564 Explanation: Maximum numeric value among 100, 564 and 365 is 564.

Input: S = abcdefg Output: -1 Explanation: Return -1 if no numeric value is present.

// C++ program to extract the maximum value
#include<bits/stdc++.h>
using namespace std;

// Function to extract the maximum value
int extractMaximum(string str)
{
	int num = 0, res = 0;

	// Start traversing the given string
	for (int i = 0; i<str.length(); i++)
	{
		// If a numeric value comes, start converting
		// it into an integer till there are consecutive
		// numeric digits
		if (str[i] >= '0' && str[i] <= '9')
			num = num * 10 + (str[i]-'0');

		// Update maximum value
		else
		{
			res = max(res, num);

			// Reset the number
			num = 0;
		}
	}

	// Return maximum value
	return max(res, num);
}

// Driver program
int main()
{
	string str = "100klh564abc365bg";
	cout << extractMaximum(str);
	return 0;
}

// C++ program for above implementation
#include<bits/stdc++.h>
using namespace std;

// Utility function to find maximum string
string maximumNum(string curr_num, string res)
{
	int len1 = curr_num.length();
	int len2 = res.length();

	// If both having equal lengths
	if (len1 == len2)
	{
		// Reach first unmatched character / value
		int i = 0;
		while (curr_num[i]== res[i])
			i++;

		// Return string with maximum value
		if (curr_num[i] < res[i])
			return res;
		else
			return curr_num;
	}

	// If different lengths
	// return string with maximum length
	return len1 < len2 ? res: curr_num;
}

// Function to extract the maximum value
string extractMaximum(string str)
{
	int n = str.length();
	string curr_num ="";
	string res;

	// Start traversing the string
	for (int i = 0; i<n; i++)
	{
		// Ignore leading zeroes
		while (i<n && str[i]=='0')
			i++;

		// Store numeric value into a string
		while (i<n && str[i]>='0' && str[i]<='9')
		{
			curr_num = curr_num + str[i];
			i++;
		}

		if (i == n)
			break;

		if (curr_num.size() > 0)
			i--;

		// Update maximum string
		res = maximumNum(curr_num, res);

		curr_num = "";
	}

	// To handle the case if there is only
	// 0 numeric value
	if (curr_num.size()== 0 && res.size()== 0)
		res = res + '0';

	// Return maximum string
	return maximumNum(curr_num, res);
}

// Drivers program
int main()
{
	string str ="100klh564abc365bg";
	cout << extractMaximum(str) << endl;
	return 0;
}