poj3274 hash数组

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#include <iostream>#include <cstdio>#include <cstring>#define N 100001#define Prime 99983using namespace std;int n, k, flag[N][31], c[N][31], hash[Prime];inline int hashcode(const int *v){        int s = 0;        for(int i = 0; i < k; i++)                s=((s << 2) + (v[i] >> 4)) ^ (v[i] << 10);        s = s % Prime;        s = s < 0 ? s + Prime : s;        return s;}int main(){        int i, j, tmp, maximum = 0;        scanf("%d%d", &n, &k);        memset(flag, 0, sizeof(flag));        memset(c, 0, sizeof(c));        memset(hash, -1, sizeof(hash));        hash[hashcode(c[1])] = 0;        for (i = 1; i <= n; i++)        {                scanf("%d", &tmp);                for (j = 0; j < k; j++)                {                        if ((tmp >> j) & 1)     flag[i][j] = flag[i - 1][j] + 1;                        else flag[i][j] = flag[i - 1][j];                        c[i][j] = flag[i][j] - flag[i][0];                }                tmp = hashcode(c[i]);                while (hash[tmp] != -1)                {                        for (j = 1; j < k; j++)                                if (c[i][j] != c[hash[tmp]][j]) break;                        if (j >= k)                        {                                j = i - hash[tmp];                                maximum = maximum > j ? maximum : j;                                break;                        }                        tmp++;                }                if (hash[tmp] == -1) hash[tmp] = i;        }        printf("%d\n", maximum);        return 0;}
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