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=0; i < ransomNote.length();++i)
{
mpr[ransomNote[i]]++;
}
for(j = 0; 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;

}
};