hdu5183---Negative and Positive (NP)(HASHMAP)

Problem Description
When given an array (a0,a1,a2,?an?1) and an integer K, you are expected to judge whether there is a pair (i,j)(0≤i≤j

/*************************************************************************
    > File Name: hdu5183.cpp
    > Author: ALex
    > Mail: zchao1995@gmail.com 
    > Created Time: 2015年03月08日 星期日 19时55分52秒
 ************************************************************************/

#include <map>
#include <set>
#include <queue>
#include <stack>
#include <vector>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;

const double pi = acos(-1);
const int inf = 0x3f3f3f3f;
const double eps = 1e-15;
typedef long long LL;
typedef pair <int, int> PLL;

const int maxn = 1000007;

int A[1000010];

struct HASHMAP
{
    int head[maxn], next[maxn], size;
    LL sta[maxn];

    void init ()
    {
        size = 0;
        memset (head, -1, sizeof(head));
    }

    bool check (LL val)
    {
        int h = (val % maxn + maxn) % maxn;
        for (int i = head[h]; ~i; i = next[i])
        {
            if (val == sta[i])
            {
                return true;
            }
        }
        return false;
    }

    int insert (LL val)
    {
        int h = (val % maxn + maxn) % maxn;
        for (int i = head[h]; ~i; i = next[i])
        {
            if (val == sta[i])
            {
                return true;
            }
        }
        sta[size] = val;
        next[size] = head[h];
        head[h] = size++;
        return false;
    }
}H1, H2;

template <class T>
bool scan_d (T &ret)
{
    char c;
    int sgn;
    T bit = 0.1;
    if (c = getchar(), c == EOF)
    {
        return 0;
    }
    while (c != ‘-‘ && c != ‘.‘ && (c < ‘0‘ || c > ‘9‘))
    {
        c = getchar ();
    }
    sgn = (c == ‘-‘) ? -1 : 1;
    ret = (c == ‘-‘) ? 0 : (c - ‘0‘);
    while (c = getchar (), c >= ‘0‘ && c <= ‘9‘)
    {
        ret = ret * 10 + (c - ‘0‘);
    }
    if (c == ‘ ‘ || c == ‘\n‘)
    {
        ret *= sgn;
        return 1;
    }
    while (c = getchar(), c >= ‘0‘ && c <= ‘9‘)
    {
        ret += (c - ‘0‘) * bit, bit /= 10;
    }
    ret *= sgn;
    return 1;
}

int main ()
{
    int t;
    int icase = 1;
    scanf("%d", &t);
    while (t--)
    {
        H1.init();
        H2.init();
        int n;
        scanf("%d", &n);
        LL k;
        scanf("%lld", &k);
        H1.insert (0);
        LL s = 0;
        bool flag = 0;
        for (int i = 0; i < n; ++i)
        {
            scan_d(A[i]);
        }
        for (int i = 0; i < n; ++i)
        {
            if (i & 1)
            {
                s -= A[i];
            }
            else
            {
                s += A[i];
            }
            if (i & 1)
            {
                H1.insert (s);
            }
            else
            {
                H2.insert (s);
            }
            if (H1.check (s - k) || H2.check (s + k))
            {
                flag = 1;
                break;
            }
        }
        printf("Case #%d: ", icase++);
        if (flag)
        {
            printf("Yes.\n");
        }
        else
        {
            printf("No.\n");
        }
    }
    return 0;
}