Merge Array

/***
In given array of elements like [a1,a2,a3,..an,b1,b2,b3,..bn,c1,c2,c3,...cn]
Write a program to merge them like [a1,b1,c1,a2,b2,c2,...an,bn,cn].
PS: Doing without using extra memory would fetch more points

Sample Testcases:
Input #00:
{1,2,3,4,5,6,7,8,9,10,11,12}

Output #00:
{1,5,9,2,6,10,3,7,11,4,8,12}

Explanation:
Here as you can notice, the array is of the form
{a1,a2,a3,a4,b1,b2,b3,b4,c1,c2,c3,c4}
***/

#include<iostream>
#include<string>
#include<map>
#include <vector>

using namespace std;

class mergeArray {
public:
       mergeArray(string *str, int size);
       ~mergeArray();
       void arrangementArray();
       void print();

private:
       map<int, vector<int>> mymap;
       string *mystr;
       int sz;      
};

mergeArray::mergeArray(string *str, int size) {
       mystr = str;
       sz = size;
       //initial map;
       mymap.clear();
}

mergeArray::~mergeArray() {
       mymap.clear();
}

void mergeArray::arrangementArray() {
       map<int, vector<int>>::iterator it;
       int id;
       for(int i = 0; i<sz; i++) {
              string s = mystr[i];
      
              //Note: direct access the number..
              id = atoi(s.c_str()+1);
              it = mymap.find(id);
              if(it != mymap.end()) {
                     it->second.push_back(i);
              } else {
                     vector<int> v;
                     v.push_back(i);
                     mymap.insert(pair<int, vector<int>>(id, v));
              }
       }
}

void mergeArray::print() {
       map<int, vector<int>>::iterator it;
       for(it = mymap.begin(); it != mymap.end(); it++) {
              vector<int> v = it->second;
              for(int i = 0; i < v.size(); i++)
                     cout<<mystr[v[i]]<<" ";
       }
       cout<<endl;
}

void main() {

       string str[] = {"a1","a2","a3","a4","b1","b2","b3","b4","c1","c2","c3","c4"};
       int sz = sizeof(str) / sizeof(string);
       mergeArray mga(str, sz);
       mga.arrangementArray();
       mga.print();

}

Comments

  1. AdaAugust 19, 2013 at 8:34 AM

    Space Complexity is O(n), should be done with O(1)...

    ReplyDelete

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