CODEWITHSUNDEEP
javastringmathsplitreverse
Voldermont Lord
Voldermont Lord

Reputation: 11

reversing every odd string and adding them together

i want to reverse every odd pair of strings and them add them together with the even pair.

for example the string 123456789 would turn into 213465789 and then adding them together would give 21+34+65+78+9 which = 207.

my current code is 

public static void main(String[] args) {
    String Num = "123456789";
    System.out.println(reverse(Num) + ".");
} 

public static int reverse(String a) {
    String newa = "";
    String revString = "";
    char ch;
    for (int i = 0; i < a.length(); i=i+4) {
        newa = (a.substring(i, i + 2));
        ch = newa.charAt(i);
        revString = ch + revString;
       }
    }

I do have an general idea which is to reverse every second pair of strings and place them back into a new string that would be "213465789". Then split the string into pairs and add them up and whatever other operation like /, * and % but i cant seem to write my code

Thanks in advance

Upvotes: 0

Views: 297

Answers (2)

NoobEditor
NoobEditor

Reputation: 15891

Simply algo would be something like

  • String Num = "123456789";

  • Loop for(int i= 0 to n-3;i=i+2) - to reverse the string

  • swap i with i+1 - this give alternate rev string

  • again for(int i= 0 to n-3;i=i+2) - to add the sum

  • sum = sum + ((chatAt(i)-'0')*10+(charAt(i+1)-'0')) - typecast from char to int using [char]-'0' logic, for String "21", logic would be to have (2*10+1)

Upvotes: 0

Subhrajyoti Majumder
Subhrajyoti Majumder

Reputation: 41200

try this - 

int pairCout=0;
int sum =0;
for (int i = 0; i < a.length();i+=2) {
        String newa = a.substring(i, (i + 2)<a.length()?(i+2):a.length());
        pairCout++;
        if(pairCout%2 ==0){     // EVEN/ODD separation
            String reverse = new StringBuilder(newa ).reverse().toString();
            sum+=Integer.parseInt(reverse); // SUMMATION
        }else{
            sum+=Integer.parseInt(newa );  // SUMMATION
        }
}

Just an approach - OUTPUT - 207

Upvotes: 1

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