hdu 5282 序列计数

 1 #include "bits/stdc++.h"
 2 using namespace std;
 3 int T;
 4 char s1[1010], s2[1010];
 5 int dp[1010][1010];
 6 long long Count[1010][1010];
 7 const long long MOD = 1000000007;
 8 
 9 int main()
10 {
11     int len1, len2;
12     scanf("%d", &T);
13     while(T--) {
14         memset(dp, 0, sizeof(dp));
15         memset(Count, 0, sizeof(Count));
16         scanf("%s", s1 + 1);
17         scanf("%s", s2 + 1);
18         len1 = strlen(s1 + 1);
19         len2 = strlen(s2 + 1);
20         int i, j;
21 
22         for(i = 0; i <= len1; ++i) {
23             Count[i][0] = 1;
24         }
25         for(j = 0; j <= len2; ++j) {
26             Count[0][j] = 1;
27         }
28 
29         for(i = 1; i <= len1; ++i) {
30             int k = 0, p = 0;
31             for(j = 1; j <= len2; ++j) {
32 //                printf("%d %d\n", i, j);
33 //                if(s1[i] == s2[j]) {
34 //                    dp[i][j] = dp[i - 1][k] + 1;
35 //                }
36 //                else {
37 //                    dp[i][j] = dp[i - 1][j];
38 //                }
39 //                if(dp[i - 1][k] < dp[i - 1][j]) {
40 //                    k = j;
41 //                }
42                 if(s1[i] == s2[j]) {
43                     dp[i][j] = dp[i - 1][j - 1] + 1;
44                 }
45                 else {
46                     dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]);
47                 }
48 
49                 if(s1[i] == s2[j]) {
50                     p = j;
51                 }
52                 if(dp[i][j] == dp[i - 1][p - 1] + 1) {
53                     Count[i][j] += Count[i - 1][p - 1];
54                 }
55                 if(dp[i][j] == dp[i - 1][j]) {
56                     Count[i][j] += Count[i - 1][j];
57                 }
58                 Count[i][j] %= MOD;
59             }
60         }
61         printf("%lld\n", Count[len1][len2]);
62     }
63 }