二进制数位DP，涉及到数字的按位与操作。

#include 
      
       #include 
       
        #include 
        
         #include 
         
          using namespace std;#define MAX_LEN 50long long A, B, K;int a[MAX_LEN], b[MAX_LEN], k[MAX_LEN];long long memoize[MAX_LEN][2][2][2];void input(){    scanf("%lld%lld%lld", &A, &B, &K);}int convert(long long A, int a[]){    int i = 0;    while (A)    {        a[i] = A & 1;        A >>= 1;        i++;    }    return i;}long long dfs(int current_bit, bool less_a, bool less_b, bool less_k){    if (current_bit == -1)    {        if (less_a && less_b && less_k)        {            return 1;        }        return 0;    }    if (memoize[current_bit][less_a][less_b][less_k] != -1)        return memoize[current_bit][less_a][less_b][less_k];    bool one_a = less_a || a[current_bit] == 1;    bool one_b = less_b || b[current_bit] == 1;    bool one_k = less_k || k[current_bit] == 1;    // a0 b0    long long ret = dfs(current_bit - 1, one_a, one_b, one_k);    // a1 b0    if (one_a)    {        ret += dfs(current_bit - 1, less_a, one_b, one_k);    }    // a0 b1    if (one_b)    {        ret += dfs(current_bit - 1, one_a, less_b, one_k);    }    // a1 b1    if (one_a && one_b && one_k)    {        ret += dfs(current_bit - 1, less_a, less_b, less_k);    }    return memoize[current_bit][less_a][less_b][less_k] = ret;}int main(){    int t;    scanf("%d", &t);    for (int i = 0; i < t; i++)    {        printf("Case #%d: ", i + 1);        input();        memset(a, 0, sizeof(a));        memset(b, 0, sizeof(b));        memset(k, 0, sizeof(k));        convert(A, a);        convert(B, b);        convert(K, k);        memset(memoize, -1, sizeof(memoize));        long long ans = dfs(31, false, false, false);        printf("%lld\n", ans);    }    return 0;}