leetcode刷题，总结，记录，备忘 383

leetcode383  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

遍历第一个字符串，将每个字符在第二个字符串中查找没有的话就返回错，找到的话就继续并在第二个字符串中将这个字符删除掉，继续遍历。
class Solution {
public:
bool canConstruct(string ransomNote, string magazine) {
for (int i = 0; i < ransomNote.size(); ++i)
{
char c = ransomNote[i];
int pos;
if ((pos = magazine.find(c)) == string::npos)
{
return false;
}

magazine.erase(pos, 1);
}

return true;
}
};