Hash

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1 HDU 1880 魔咒词典

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <algorithm>
#include <queue>
#include <vector>
#include <stack>
#include <map>
#include <set>
#include <cmath>
#include <cctype>
#include <ctime>

using namespace std;

#define REP(i, n) for (int i = 0; i < (n); ++i)
#define eps 1e-9
#define PI acos(-1.0)
#define lc id << 1
#define rc id << 1 | 1
#define lson low, mid, lc
#define rson mid + 1, high, rc

typedef long long ll;
typedef pair<int, int> pii;
typedef unsigned int uint;

const int INF = 0x7fffffff;
const int mod = 1e5 + 7;
const int maxn = 1e5 + 10;
struct Ans { char str1[25], str2[85]; };

char opt[120], str_t[2][90];
Ans ans[2][maxn];
int Next[2][maxn], hash_table[2][maxn], cur[2];
int len, n, cnt1, cnt2;

uint BKDR_Hash(char *str) {
    uint hash = 0;
    while (*str) { hash = hash * 131 + (*str++); }
    return (hash & 0x7fffffff) % mod;
}
void insert(int flag) {
    int t = BKDR_Hash(str_t[flag]);
    strcpy(ans[flag][cur[flag]].str1, str_t[0]); strcpy(ans[flag][cur[flag]].str2, str_t[1]);
    Next[flag][cur[flag]] = hash_table[flag][t]; hash_table[flag][t] = cur[flag]++;
}
inline void print(char *str) {
    if (str[0] != '[') { printf("%s
", str); return; } len = strlen(str);
    for (int i = 1; i < len - 1; ++i) { printf("%c", str[i]); } printf("
");
}

int main() {
#ifdef __AiR_H
    freopen("in.txt", "r", stdin);
//    freopen("out.txt", "w", stdout);
#endif // __AiR_H
    memset(hash_table, -1, sizeof(hash_table)); int t; bool flag; int key;
    while (gets(opt) && opt[0] != '@') {
        len = strlen(opt); cnt1 = cnt2 = 0; int i = 0;
        memset(str_t, 0, sizeof(str_t));
        for (; opt[i] != ']'; ++i) { str_t[0][cnt1++] = opt[i]; } str_t[0][cnt1++] = ']';
        for (i += 2; i < len; ++i) { str_t[1][cnt2++] = opt[i]; }
        insert(0); insert(1);
    }
    scanf("%d", &n); getchar();
    while (n--) {
        gets(opt); flag = false; key = 0; if (opt[0] != '[') { key = 1; }
        t = BKDR_Hash(opt); t = hash_table[key][t];
        while (t != -1) {
            if (key == 0) {
                if (strcmp(opt, ans[key][t].str1) == 0) {
                    print(ans[key][t].str2); flag = true; break;
                }
            } else {
                if (strcmp(opt, ans[key][t].str2) == 0) {
                    print(ans[key][t].str1); flag = true; break;
                }
            }
            t = Next[key][t];
        }
        if (!flag) { printf("what?
"); }
    }
#ifdef __AiR_H
    printf("Time used = %.2fs
", (double)clock() / CLOCKS_PER_SEC);
#endif // __AiR_H
    return 0;
}

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1 POJ 3349 Snowflake Snow Snowflakes

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <algorithm>
#include <queue>
#include <vector>
#include <stack>
#include <map>
#include <set>
#include <cmath>
#include <cctype>
#include <ctime>

using namespace std;

typedef long long ll;
typedef unsigned int uint;
const int maxn = 10;
const int mod = 1e5 + 7;
int n, cur = 0;
int a[maxn], a_t[maxn], s_t[maxn];
int key[maxn][mod * 2], Next[mod * 2], head[mod * 2];

int get_min(int s[]) {
    int i = 0, j = 1, k = 0, t;
    while (i < 6 && j < 6 && k < 6) {
        t = s[(i + k) % 6] - s[(j + k) % 6];
        if (!t) { ++k; continue; }
        if (t > 0) { i += k + 1; } else { j += k + 1; }
        if (i == j) { ++j; } k = 0;
    }
    return min(i, j);
}
uint cal(int s[]) {
    int t = get_min(s); uint ret = 0;
    for (int i = t, j = 0; j < 6; i = (i + 1) % 6, ++j) {
        ret = ret * 131 + s[i]; s_t[j] = s[i];
    }
    for (int i = 0; i < 6; ++i) { s[i] = s_t[i]; }
    return ret % mod;
}
void insert(int x, int s[]) {
    for (int i = 0; i < 6; ++i) { key[i][cur] = s[i]; }
    Next[cur] = head[x]; head[x] = cur++;
}
bool check_t(int s[], int k) {
    for (int i = 0; i < 6; ++i) {
        if (s[i] != key[i][k]) { return false; }
    }
    return true;
}
bool check(int x, int s[]) {
    x = head[x];
    while (x != -1) {
        if (check_t(s, x)) { return true; } x = Next[x];
    }
    return false;
}

int main() {
#ifdef __AiR_H
    freopen("in.txt", "r", stdin);
//    freopen("out.txt", "w", stdout);
#endif
    scanf("%d", &n); bool flag = false; int t1, t2;
    memset(head, -1, sizeof(head));
    while (n--) {
        for (int i = 0; i < 6; ++i) { scanf("%d", &a[i]); a_t[i] = a[i]; }
        if (flag) { continue; } reverse(a_t, a_t + 6);
        t1 = cal(a); if (check(t1, a)) { flag = true; continue; }
        t2 = cal(a_t); if (check(t2, a_t)) { flag = true; continue; }
        insert(t1, a); insert(t2, a_t);
    }
    if (flag) { printf("Twin snowflakes found.
"); }
    else { printf("No two snowflakes are alike.
"); }
    return 0;
}

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