LeetCode oj 383. Ransom Note(哈希）

383. Ransom Note

 

Question
Editorial Solution
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Difficulty: Easy
Contributors: Admin


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

给你两个字符串，问第一个字符串能不能由第二个字符串中的字符组成

水的不行，哈希存一下就行了。

public class Solution {
public boolean canConstruct(String ransomNote, String magazine) {
int hash_r[] = new int [256];
int hash_m[] = new int [256];
int len_r = ransomNote.length();
int len_m = magazine.length();
if(len_r > len_m)
return false;
for(int i=0;i<len_r;i++){
hash_r[ransomNote.charAt(i)-'a']++;
};
for(int i=0;i<len_m;i++){
hash_m[magazine.charAt(i)-'a']++;
}
int flag = 0;
for(int i=0;i<len_r;i++){
if(hash_m[ransomNote.charAt(i)-'a'] < hash_r[ransomNote.charAt(i)-'a']){
flag = 1;
break;
}
}
if(flag == 1)
return false;
else
return true;
}
}