Maximum segment value after putting k breakpoints in a number

Given a large number as string s and an integer k which denotes the number of breakpoints we must put in the number k <= string length. The task is to find maximum segment value after putting exactly k breakpoints.

Examples:

Input : s = "8754", k = 2
Output : Maximum number = 87
Explanation : We need to two breakpoints. After
putting the breakpoints, we get following options
8 75 4
87 5 4
The maximum segment value is 87.

Input : s = "999", k = 1 
Output : Maximum Segment Value = 99
Explanation : We need to one breakpoint. After
putting the breakpoint, we either get 99,9 or
9,99.



One important observation is, the maximum would always be of length “string-length – k” which is the maximum value of any segment. Considering the fact, problem becomes like sliding window problem means we need to find maximum of all substrings of size (string-length – k).

C++

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// CPP program to find the maximum segment
// value after putting k breaks.
#include <bits/stdc++.h>
using namespace std;
  
// Function to Find Maximum Number
int findMaxSegment(string &s, int k) {
  
  // Maximum segment length
  int seg_len = s.length() - k;
  
  // Find value of first segment of seg_len
  int res = 0;
  for (int i=0; i<seg_len; i++)
     res = res * 10 + (s[i] - '0');
  
  // Find value of remaining segments using sliding
  // window
  int seg_len_pow = pow(10, seg_len-1);
  int curr_val = res;
  for (int i = 1; i <= (s.length() - seg_len); i++) {
  
    // To find value of current segment, first remove
    // leading digit from previous value    
    curr_val = curr_val - (s[i-1]- '0')*seg_len_pow;
  
    // Then add trailing digit
    curr_val = curr_val*10 + (s[i+seg_len-1]- '0');
  
    res = max(res, curr_val);
  }
  return res;
}
  
// Driver's Function
int main() {
  string s = "8754";
  int k = 2;
  cout << "Maximum number = " << findMaxSegment(s, k);
  return 0;
}

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Java

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// Java program to find the maximum segment
// value after putting k breaks.
class GFG {
      
    // Function to Find Maximum Number
    static int findMaxSegment(String s, int k) {
      
        // Maximum segment length
        int seg_len = s.length() - k;
      
        // Find value of first segment of seg_len
        int res = 0;
          
        for (int i = 0; i < seg_len; i++)
            res = res * 10 + (s.charAt(i) - '0');
      
        // Find value of remaining segments using 
        // sliding window
        int seg_len_pow = (int)Math.pow(10,
                                    seg_len - 1);
        int curr_val = res;
          
        for (int i = 1
             i <= (s.length() - seg_len); i++) {
      
            // To find value of current segment, 
            // first remove leading digit from 
            // previous value
            curr_val = curr_val - 
            (s.charAt(i - 1) - '0') * seg_len_pow;
          
            // Then add trailing digit
            curr_val = curr_val * 10
               (s.charAt(i + seg_len - 1) - '0');
          
            res = Math.max(res, curr_val);
        }
          
        return res;
    }
      
    // Driver code
    public static void main(String[] args) {
          
        String s = "8754";
        int k = 2;
          
        System.out.print("Maximum number = "
                        + findMaxSegment(s, k));
    }
}
  
// This code is contributed by Anant Agarwal.

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Python3

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# Python3 program to find the maximum segment 
# value after putting k breaks. 
  
# Function to Find Maximum Number 
def findMaxSegment(s, k):
  
    # Maximum segment length 
    seg_len = len(s) -
  
    # Find value of first segment of seg_len 
    res = 0
    for i in range(seg_len):
        res = res * 10 + (ord(s[i]) - ord('0')) 
  
    # Find value of remaining segments
    # using sliding window 
    seg_len_pow = pow(10, seg_len - 1
    curr_val = res 
    for i in range(1, len(s) - seg_len):
  
        # To find value of current segment, 
        # first remove leading digit from 
        # previous value     
        curr_val = curr_val - (ord(s[i - 1])- 
                               ord('0')) * seg_len_pow 
  
        # Then add trailing digit 
        curr_val = (curr_val * 10 + 
                   (ord(s[i + seg_len - 1]) - ord('0'))) 
  
        res = max(res, curr_val)
    return res
  
# Driver Code
if __name__ == '__main__':
    s = "8754"
    k = 2
    print("Maximum number = ",
         findMaxSegment(s, k))
  
# This code is contributed by PranchalK

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C#

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// C# program to find the maximum segment
// value after putting k breaks.
using System;
  
class GFG {
      
    // Function to Find Maximum Number
    static int findMaxSegment(string s, int k) {
      
        // Maximum segment length
        int seg_len = s.Length - k;
      
        // Find value of first segment of seg_len
        int res = 0;
          
        for (int i = 0; i < seg_len; i++)
            res = res * 10 + (s[i] - '0');
      
        // Find value of remaining segments using 
        // sliding window
        int seg_len_pow = (int)Math.Pow(10,
                                    seg_len - 1);
        int curr_val = res;
          
        for (int i = 1; 
            i <= (s.Length- seg_len); i++) {
      
            // To find value of current segment, 
            // first remove leading digit from 
            // previous value
            curr_val = curr_val - 
            (s[i - 1] - '0') * seg_len_pow;
          
            // Then add trailing digit
            curr_val = curr_val * 10 + 
            (s[i + seg_len - 1] - '0');
          
            res = Math.Max(res, curr_val);
        }
          
        return res;
    }
      
    // Driver code
    public static void Main() {
          
        String s = "8754";
        int k = 2;
          
        Console.WriteLine("Maximum number = "
                        + findMaxSegment(s, k));
    }
}
  
// This code is contributed by vt_m.

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Output:

Maximum number = 87


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