bzoj1055: [HAOI2008]玩具取名

题目链接

bzoj1055: [HAOI2008]玩具取名

题解

f[l][r][k]表示l-r能否合成字母k
由枚举自己可能的分解转移得到
记忆化搜索好写些

代码

#include<cstdio> 
#include<cstring>
#include<algorithm> 
 
inline int read() {
    int x = 0,f = 1;
    char c = getchar(); 
    while(c < '0' || c > '9') {if(c == '-')f = -1;c = getchar();} 
    while(c <= '9' && c >= '0') x = x * 10 + c - '0',c = getchar();
    return x * f;
} 
const int maxn = 17;
const int maxm = 207; 
int mp[maxm]; 
char is[maxn] = {'W','I','N','G'}; 
int ID[5];  
char a[5][maxm][2],t[maxm]; 
int f[maxm][maxm][maxn]; 
bool dp (int l,int r,int k) { 
    if(l == r) return t[l] == is[k]; 
    int & ret = f[l][r][k]; 
    if(ret != -1) return ret; 
    for(int i = 1;i <= ID[k];++ i) 
        for(int j = l;j <= r - 1;++ j) 
            if( dp(l,j,mp[a[k][i][0]]) && dp(j + 1,r,mp[a[k][i][1]]))
                return ret = 1;
    return ret = 0;
}
int main() {            
    memset(f,-1,sizeof f);
    for(int i = 0;i < 4;++ i) ID[i] = read(); 
    for(int i = 0;i < 4;++ i) 
        for(int j = 1;j <= ID[i];++ j) scanf("%s",a[i][j]); 
    scanf("%s",t + 1); 
    mp['W'] = 0,mp['I'] = 1,mp['N'] = 2,mp['G'] = 3; 
    int len = strlen(t + 1); bool flag = 0; 
    for(int i = 0;i < 4;++ i) 
        if(dp(1,len,i)) printf("%c",is[i]),flag = 1; 
    if(! flag)puts("The name is wrong!"); 
    return 0;
}