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  • Java [Leetcode 383]Ransom Note

    题目描述:

    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

    解题思路:

    开26个数组存入magzine字母的数目,每个位置存对应字母的数目;

    对ransom字符串来说,每读一个字母,则将对应位置的字母数目减一,如果某个字母数目小于0了,则表明字母不够用,从而返回false;否则返回true。

    代码如下:

    public class Solution {
        public boolean canConstruct(String ransomNote, String magazine) {
        	int[] ran_array = new int[26];
        	for(int i = 0; i < magazine.length(); i++){
        		ran_array[magazine.charAt(i) - 'a']++;
        	}
    
        	for(int i = 0; i < ransomNote.length(); i++){
        		if(--ran_array[ransomNote.charAt(i) - 'a'] < 0)
        			return false;
        	}
    
        	return true;
            
        }
    }
    

      

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  • 原文地址:https://www.cnblogs.com/zihaowang/p/5778378.html
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