解题思路:
注意事项:
参考代码:
import java.util.Arrays;
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
char[] arr1 = scan.nextLine().toCharArray();
int[] arr2 = new int[26];
long count = 0;
int index;
long len = arr1.length;
Arrays.fill(arr2, -1);
for (int i = 0; i < arr1.length; i++) {
index = arr1[i] - 'a';
count += (len - i) * (i - arr2[index]);
arr2[index] = i;
}
System.out.println(count);
}
}
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