leetcode 383. Ransom Note


Given
 an 
arbitrary
 ransom
 note
 string 
and 
another 
string 
containing 
letters from
 all 
the 
magazines,
 write 
a 
function 
that 
will 
return 
true 
if 
the 
ransom 
 note 
can 
be 
constructed 
from 
the 
magazines ; 
otherwise, 
it 
will 
return 
false. 



Each 
letter
 in
 the
 magazine 
string 
can
 only 
be
 used 
once
 in
 your 
ransom
 note.

Note:
You may assume that both strings contain only lowercase letters.

canConstruct("a", "b") -> false
canConstruct("aa", "ab") -> false
canConstruct("aa", "aab") -> true

 class Solution {
 public:
     bool canConstruct(string ransomNote, string magazine) {
         map<char,int> mpr,mpm;
         map<char,int>::iterator itr,itm;
         int i ,j;
         for(i=; i < ransomNote.length();++i)
         {
             mpr[ransomNote[i]]++;
         }
         for(j = ; j<magazine.length();++j)
         {
             mpm[magazine[j]]++;
         }
         if(mpr.size() > mpm.size()) return false;
         itr = mpr.begin();itm = mpm.begin();
         while(itr != mpr.end() && itm != mpm.end())
         {
             char tmp = itr->first;
             map<char,int>::iterator t;

             if(mpm.find(tmp) == mpm.end())
                 return false;

             if((int)(itr->second) > (int)(mpm.find(tmp)->second))
                 return false;
             else
                 itr++;
         }
         return true;

     }
 };