BZOJ2423 [HAOI2010]最长公共子序列

第一问是裸DP。。。。

第二问还是裸DP，注意一种特殊情况（我忘了是什么特殊情况了QAQQQ）

滚动数组可以压掉一维，而且 ^ (xor)比 ! (not)慢。。。

 

/**************************************************************
    Problem: 2423
    User: rausen
    Language: C++
    Result: Accepted
    Time:964 ms
    Memory:892 kb
****************************************************************/
 
#include <cstdio>
#include <cstring>
#include <algorithm>
  
using namespace std;
const int N = 5005;
const int mod = 100000000;
int f[2][N], g[2][N];
int l1, l2, cur, i, j;
char s1[N], s2[N];
  
void read(){
    char ch = getchar();
    while ((ch < 'A' || ch > 'Z') && ch != '.')
        ch = getchar();
    while (ch != '.')
        s1[++l1] = ch, ch = getchar();
    ch = getchar();
    while ((ch < 'A' || ch > 'Z') && ch != '.')
        ch = getchar();
    while (ch != '.')
        s2[++l2] = ch, ch = getchar();
}
  
int main(){
    read();
    for (j = 0; j <= l2; ++j)
        g[0][j] = 1;
    g[1][0] = 1;
    cur = 0;
    for (i = 1; i <= l1; ++i)
        for (j = 1, cur ^= 1; j <= l2; ++j)
            if (s1[i] == s2[j]){
                f[cur][j] = f[!cur][j - 1] + 1;
                g[cur][j] = g[!cur][j - 1];
                if (f[cur][j] == f[cur][j - 1])
                    g[cur][j] += g[cur][j - 1], g[cur][j] %= mod;
                if (f[cur][j] == f[!cur][j])
                    g[cur][j] += g[!cur][j], g[cur][j] %= mod;
            }else{
                f[cur][j] = f[!cur][j], g[cur][j] = g[!cur][j];
                if (f[cur][j] < f[cur][j - 1]){
                    f[cur][j] = f[cur][j - 1];
                    g[cur][j] = g[cur][j - 1];
                }else if (f[cur][j] == f[cur][j - 1]){
                    g[cur][j] += g[cur][j - 1];
                    if (f[!cur][j - 1] == f[cur][j])
                        g[cur][j] -= g[!cur][j - 1];
                    g[cur][j] %= mod;
                }
            }
    printf("%d\n%d\n", f[cur][l2] % mod, g[cur][l2] % mod);
    return 0;
}