#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn=1010;
int next[maxn];
int l1=15,l2=3;//两串长度
char str1[maxn]="abcaccdeacdaacd",str2[maxn]="acd";
int sum;
void get_next()
{//next数组保存了以i结尾的字符串的最长公共前缀和后缀的起始坐标
int i,j;
next[0] = j = -1;
i = 0;
while(i < l2)
{
while(j!=-1&&str2[j]!=str2[i])//自身和自身进行匹配
j = next[j];
next[++i] = ++j;
}
}
int kmp1()//找出现位置
{
int i,j;
i = j = 0;
while(i < l1&&j<l2)
{
while(j!=-1&&str1[i]!=str2[j])
{
j = next[j];
}
i++;
j++;
}
if(j == l2)
return i-j;//完全匹配时的开始下标,下标从0开始
return -1;//不存在匹配情况
}
int kmp2()//找出现次数
{
int i,j;
i = j = 0;
while(i < l1)//注意和返回下标的区别
{
while(j!=-1&&str1[i]!=str2[j])
{
j = next[j];
}
if(j == l2-1)
{
sum ++;
j = next[j];
}
i++;
j++;
}
return sum;//返回匹配次数
}
int main()
{
get_next();
int ans1=kmp1();
int ans2=kmp2();
cout<<ans1<<" "<<ans2<<endl;
}
输出
8 2