线型dp

Posted 2020-10-09 __AiR_H

1 Codeforces 118D Caesar‘s Legions

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <cstdlib>
 5 #include <algorithm>
 6 #include <queue>
 7 #include <vector>
 8 #include <stack>
 9 #include <map>
10 #include <set>
11 #include <cmath>
12 #include <cctype>
13 #include <ctime>
14 
15 using namespace std;
16 
17 #define REP(i, n) for (int i = 0; i < (n); ++i)
18 #define eps 1e-9
19 #define SZ(x) ((int)x.size())
20 
21 typedef long long ll;
22 typedef pair<int, int> pii;
23 const int mod = 1e8;
24 int n1, n2, k1, k2;
25 int dp[105][105][15][15];
26 
27 int main() {
28 #ifdef __AiR_H
29     freopen("in.txt", "r", stdin);
30 //    freopen("out.txt", "w", stdout);
31 #endif // __AiR_H
32     scanf("%d %d %d %d", &n1, &n2, &k1, &k2); int ans = 0;
33     for (int i = 1; i <= min(n1, k1); ++i) { dp[i][0][i][0] = 1; }
34     for (int i = 1; i <= min(n2, k2); ++i) { dp[0][i][0][i] = 1; }
35     for (int i = 1 ; i <= n1; ++i) {
36         for (int j = 1; j <= n2; ++j) {
37             for (int k = 1; k <= min(j, k2); ++k) {
38                 dp[i][j][1][0] += dp[i - 1][j][0][k];
39                 dp[i][j][1][0] %= mod;
40             }
41             for (int k = 1; k <= min(i, k1); ++k) {
42                 dp[i][j][0][1] += dp[i][j - 1][k][0];
43                 dp[i][j][0][1] %= mod;
44             }
45             for (int k = 2; k <= min(k1, i); ++k) {
46                 dp[i][j][k][0] += dp[i - 1][j][k - 1][0];
47                 dp[i][j][k][0] %= mod;
48             }
49             for (int k = 2; k <= min(k2, j); ++k) {
50                 dp[i][j][0][k] += dp[i][j - 1][0][k - 1];
51                 dp[i][j][0][k] %= mod;
52             }
53         }
54     }
55     for (int i = 1; i <= min(n1, k1); ++i) {
56         ans += dp[n1][n2][i][0]; ans %= mod;
57     }
58     for (int i = 1; i <= min(n2, k2); ++i) {
59         ans += dp[n1][n2][0][i]; ans %= mod;
60     }
61     printf("%d\n", ans);
62 #ifdef __AiR_H
63     printf("Time used = %.2fs\n", (double)clock() / CLOCKS_PER_SEC);
64 #endif // __AiR_H
65     return 0;
66 }

View Code