codeforces808G. Anthem of Berland

傳送門

題意:給定兩個字符串s(1e5)和t(1e5),s中可能包含小寫字母和?,t中只包含小寫字母,求s中最多能包含幾次t

kmp+dp,每次匹配成功時,往前遍歷一遍fail數組轉移重疊的情況

#include<cstdio>
#include<cstring>
char s1[100007],s2[100007];
int fa[100007],f[100007],g[100007];
bool is[100007];
void maxs(int&a,int b){if(a<b)a=b;}
int main(){
	scanf("%s%s",s1+1,s2+1);
	int l1=strlen(s1+1),l2=strlen(s2+1);
	for(int i=2,j=0;i<=l2;++i){
		while(j&&s2[i]!=s2[j+1])j=fa[j];
		if(s2[i]==s2[j+1])++j;
		fa[i]=j;
	}
	for(int i=l2;i<=l1;++i){
		is[i]=1;
		for(int a=0;a<l2;++a)if(s1[i-a]!='?'&&s1[i-a]!=s2[l2-a]){
			is[i]=0;
			break;
		}
		g[i]=g[i-1];
		if(is[i]){
			f[i]=g[i-l2];
			for(int j=fa[l2];j;j=fa[j]){
				maxs(f[i],f[i-(l2-j)]);
			}
			++f[i];
			maxs(g[i],f[i]);
		}
	}
	printf("%d",g[l1]);
	return 0;
}