Leetcode 2744. Find Maximum Number of String Pairs
You are given a 0-indexed array words consisting of distinct strings.
The string words[i] can be paired with the string words[j] if:
The string
words[i]is equal to the reversed string ofwords[j].0 <= i < j < words.length.
Return the maximum number of pairs that can be formed from the array words.
Note that each string can belong in at most one pair.
Example 1:
Input: words = ["cd","ac","dc","ca","zz"]Output: 2Explanation: In this example, we can form 2 pair of strings in the following way: - We pair the 0th string with the 2nd string, as the reversed string of word[0] is "dc" and is equal to words[2]. - We pair the 1st string with the 3rd string, as the reversed string of word[1] is "ca" and is equal to words[3]. It can be proven that 2 is the maximum number of pairs that can be formed.
Example 2:
Input: words = ["ab","ba","cc"]Output: 1Explanation: In this example, we can form 1 pair of strings in the following way: - We pair the 0th string with the 1st string, as the reversed string of words[1] is "ab" and is equal to words[0]. It can be proven that 1 is the maximum number of pairs that can be formed.
Example 3:
Input: words = ["aa","ab"]Output: 0Explanation: In this example, we are unable to form any pair of strings.
Constraints:
1 <= words.length <= 50words[i].length == 2wordsconsists of distinct strings.words[i]contains only lowercase English letters.
找是否是反序的字符串对，用stringbuilder即可处理，
下面是代码：
import java.util.Arrays;
public class Code2744 {
public static void main(String[] args) {
}
public static int maximumNumberofStringPairs(String[]words){
boolean[]bn=new boolean[words.length];
int cnt=0;
Arrays.fill(bn, false);
for (int i = 0; i < words.length-1; i++) {
for (int j = i+1; j < words.length; j++) {
if(check(words[i], words[j])&&bn[i]==false&&bn[j]==false){
bn[i]=true;
bn[j]=true;
cnt++;
}
}
}
return cnt;
}
public static boolean check(String a, String b){
StringBuilder sb=new StringBuilder(a);
if(sb.reverse().toString().equals(b)){
return true;
}else{
return false;
}
}
}
Runtime: 8 ms, faster than 33.33% of Java online submissions for Find Maximum Number of String Pairs.
Memory Usage: 43.9 MB, less than 33.33% of Java online submissions for Find Maximum Number of String Pairs.
