美团笔试一二题，只能ac50%（反面教材，已解决）
第一题代码，递归+备忘录：
package interview;
import java.util.*;
public class Main {
static long[][] cache;
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int size = sc.nextInt();
sc.nextLine();
cache = new long[2][size];
char[][] places = new char[2][size];
places[0] = sc.nextLine().toCharArray();
places[1] = sc.nextLine().toCharArray();
long ans = walk(2 - 1, size - 1, places);
System.out.println(ans == 0 ? - 1 : ans);
}
public static long walk(int i, int j, char[][] places) {
if(i < 0 || j < 0 || i == 2 || j == places[0].length) {
return 0;
}
if(places[i][j] == 'X') {
return 0;
}
if((i == 0 && j == 0)) {
return 1;
}
if(cache[i][j] != 0) {
return cache[i][j];
}
long n = walk(i, j - 1, places) + walk(i + 1, j - 1, places) + walk(i - 1, j - 1, places);
cache[i][j] = n;
return n;
}
} 第二题，数组保存结果： package interview;
import java.util.*;
public class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
int x = sc.nextInt();
int[] nums = new int[n];
for(int i = 0; i<n; i++) {
nums[i] = sc.nextInt();
}
int[] dp = new int[1001];
for(int i = 0; i<n; i++) {
dp[nums[i]] = dp[nums[i]] + 1;
if((nums[i] | x) != nums[i]) {
dp[nums[i] | x] = dp[nums[i] | x] + 1;
}
}
int ans = 0;
for(int i = 0; i<1001; i++) {
ans = Math.max(dp[i], ans);
}
System.out.println(ans);
}
} 
