UVA 12627 – Erratic Expansion

#include <stdio.h>
#include <string.h>
#include <math.h>
#include <stdlib.h>
#include <algorithm>
#include <ctype.h>
#include <iostream>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <assert.h>
#include <time.h>
#include <sstream>

typedef long long LL;
const int INF = 500000001;
const double EPS = 1e-9;
const double PI = acos(-1.0);
using namespace std;
long long gao(int k, int a, int b)
{
    if(a > b) return 0;
    if(k == 0)
    {
        return 1;
    }
    int left = 0, right = 0;
    if(a % 2 == 0)
    {
        left = a;
        a++;
    }
    if(b % 2 == 1)
    {
        right = b;
        b--;
    }
    long long ans = gao(k-1, (a + 1) / 2, b / 2) * 2 + gao(k - 1, (a + 1) / 2, b / 2);
    if(left) ans += gao(k-1, left / 2,  left / 2);
    if(right) ans += gao(k-1, (right + 1) / 2,  (right + 1) / 2) * 2;
    return ans;
}
int main()
{
    #ifdef _Te3st
        freopen("test0.in", "r", stdin);
        freopen("test0.out", "w", stdout);
        srand(time(NULL));
    #endif
    int T, k, a, b;
    scanf("%d", &T);
    for(int i = 1; i <= T; i++)
    {
        scanf("%d %d %d", &k, &a, &b);
        printf("Case %d: %lld\n", i, gao(k, a, b));
    }
    return 0;
}