Java 实现 XOR 计数问题：动态规划解法

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        long[] A = new long[n+1];
        for (int i = 1; i <= n; i++) {
            A[i] = scanner.nextLong();
        }
        long[][] dp = new long[4][n+1];
        long[][] preV = new long[30][2];
        int mod = 998244353;

        for (int idx = 0; idx <= n; idx++) {
            dp[0][idx] = 1;
        }

        long[] two_pow = new long[30];
        for (int i = 0; i < 30; i++) {
            two_pow[i] = (long) Math.pow(2, i) % mod;
        }

        for (int k = 1; k <= 3; k++) {
            int pre = 0;
            for (int[] row : preV) {
                for (int i = 0; i < 2; i++) {
                    row[i] += dp[k - 1][0];
                }
            }
            for (int idx = 1; idx <= n; idx++) {
                pre ^= A[idx];
                long cur = 0;
                for (int c = 0; c < 30; c++) {
                    cur += preV[c][(pre >> c & 1) ^ 1] * two_pow[c];
                    cur %= mod;
                }
                dp[k][idx] = dp[k][idx - 1] + cur;
                dp[k][idx] %= mod;
                for (int c = 0; c < 30; c++) {
                    preV[c][pre >> c & 1] += dp[k - 1][idx];
                    preV[c][pre >> c & 1] %= mod;
                }
            }
        }
        System.out.println(dp[3][n]);
    }
}