洛谷 - P3375 KMP字符串匹配

传送门：洛谷 - P3375

思路分析

kmp模板

AC代码

#include <bits/stdc++.h>
#define fi first
#define se second
#define ll long long
#define pb push_back
#define mp make_pair
#define fun function
#define sz(x) (x).size()
#define lowbit(x) (x)&(-x)
#define all(x) (x).begin(),(x).end()
#define mem(a,b) memset(a,b,sizeof(a))

namespace FastIO {
#define BUF_SIZE 100000
#define OUT_SIZE 100000
    bool IOerror=0;
    inline char nc() {
        static char buf[BUF_SIZE],*p1=buf+BUF_SIZE,*pend=buf+BUF_SIZE;
        if(p1==pend) {
            p1=buf;
            pend=buf+fread(buf,1,BUF_SIZE,stdin);
            if(pend==p1) {
                IOerror=1;
                return -1;
            }
        }
        return *p1++;
    }
    inline bool blank(char ch) {
        return ch==' '||ch=='\n'||ch=='\r'||ch=='\t';
    }
    template<class T> inline bool read(T &x) {
        bool sign=0;
        char ch=nc();
        x=0;
        for(; blank(ch); ch=nc());
        if(IOerror)return false;
        if(ch=='-')sign=1,ch=nc();
        for(; ch>='0'&&ch<='9'; ch=nc())x=x*10+ch-'0';
        if(sign)x=-x;
        return true;
    }
    template<class T,class... U>bool read(T& h,U&... t) {
        return read(h)&&read(t...);
    }
#undef OUT_SIZE
#undef BUF_SIZE
};
using namespace std;
using namespace FastIO;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

const int INF = 0x3f3f3f3f;
const int N = 1e6+10;

char s[N],t[N]; 
int lens,lent;
int nex[N];

void getnext(){
    int j=0;
    nex[j]=0;
    for(int i=2;i<=lent;i++){
        while(j && t[i]!=t[j+1]) j=nex[j];
        if(t[i]==t[j+1]) j++;
        nex[i]=j;
    }
}

int main() {

#ifdef xiaofan
    freopen("1.in","r",stdin);
    freopen("1.out","w",stdout);
#endif

    cin>>s+1;
    cin>>t+1;
    lens=strlen(s+1);
    lent=strlen(t+1);
    getnext();
    
    for(int i=1,j=0;i<=lens;i++){
        while(j && s[i]!=t[j+1]) j=nex[j];
        if(s[i]==t[j+1]) j++;
        if(j==lent){
            j=nex[j];
            cout<<i-lent+1<<endl;
        }
    }
    for(int i=1;i<=lent;i++) cout<<nex[i]<<" ";




    return 0;
}