[HDU 2087]剪花布条[kmp非重叠匹配]

题意:

求一个长串最多可以被分成几个子串.

思路:

kmp, 只是不能重叠. 匹配成功后 j 回溯到 -1 而不是到 next [ j ]

#include <cstring>
#include <cstdio>
const int MAXN = 1005;
int next[MAXN],ans;
char s[MAXN];
char a[MAXN];
//0MS	204K
void prekmp()
{
    next[0] = -1;
    int j = -1;
    for(int i=1;s[i];i++)
    {
        while(j!=-1 && s[j+1]!=s[i])    j = next[j];
        if(s[j+1]==s[i])    j++;
        next[i] = j;
    }
}
void kmp()
{
    int j=-1;
    ans = 0;
    for(int i=0;a[i];i++)
    {
        while(j!=-1 && s[j+1]!=a[i])    j = next[j];
        if(s[j+1]==a[i])    j++;
        if(!s[j+1])
        {
            ans++;
            j = -1;
        }
    }
}
int main()
{
    while(scanf("%s",a) && a[0]!='#')
    {
        scanf("%s",s);
        prekmp();
        kmp();
        printf("%d\n",ans);
    }
}