[3555] [Ctsc2014]企鹅QQ（Hash）

Posted 2020-09-18 蒟蒻zht的博客

传送门

 

可以枚举被删除的位置，然后用hash表判重，然而网上好多题解都是用 sort 判重的。

不知道为什么，int 总是过不了，换成 long long 或者是 unsigned long long 就过了 QAQ

 

——代码

 1 #include <cstdio>
 2 #include <cstring>
 3 #define ULL unsigned long long
 4 #define M(a, x) memset(a, x, sizeof(a))
 5 
 6 const int p = 30011, MAXN = 40001;
 7 int n, m, k, cnt, ans;
 8 int head[MAXN], num[MAXN], next[MAXN];
 9 ULL bit[201], sum[MAXN][201], val[MAXN];
10 char s[MAXN][201];
11 
12 inline int insert(ULL x)
13 {
14     int i, a = x % p;
15     for(i = head[a]; i != -1; i = next[i])
16         if(val[i] == x)
17         {
18             num[i]++;
19             return num[i] - 1;
20         }
21     num[cnt]++;
22     val[cnt] = x;
23     next[cnt] = head[a];
24     head[a] = cnt++;
25     return 0;
26 }
27 
28 int main()
29 {
30     int i, j;
31     scanf("%d %d %d", &n, &m, &k);
32     bit[0] = 1;
33     for(i = 1; i <= m; i++) bit[i] = bit[i - 1] * 107;
34     for(i = 1; i <= n; i++) scanf("%s", s[i] + 1);
35     for(i = 1; i <= n; i++)
36         for(j = 1; j <= m; j++)
37             sum[i][j] = sum[i][j - 1] * 107 + s[i][j];
38     for(i = 1; i <= m; i++)
39     {
40         cnt = 0;
41         M(head, -1);
42         M(next, 0);
43         M(val, 0);
44         M(num, 0);
45         for(j = 1; j <= n; j++)
46             ans += insert(sum[j][m] - sum[j][i] * bit[m - i] + sum[j][i - 1] * bit[m - i + 1]);
47     }
48     printf("%d\n", ans);
49     return 0;
50 }

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