KMP算法

hdu1686http://acm.hdu.edu.cn/showproblem.php?pid=1686

可以重叠

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cstdlib>
#include<cmath>
#include<vector>
#include<stack>
#include<queue>
#define lson l, m, rt<<1
#define rson m+1, r, rt<<1|1
#define IO ios::sync_with_stdio(false);cin.tie(0);
#define INF 1e9
#define MAXN 500010
const int MOD=1e9+7;
typedef long long ll;
using namespace std;
int n, Next[10010], cnt;
char s[1000010], p[10010];
void cal_Next()
{
    int k = -1, len = strlen(p);
    Next[0] = -1;
    for(int i = 1; i < len; i++){
        while(k > -1&&p[k+1] != p[i]){
            k = Next[k];//核心 
        }
        if(p[k+1] == p[i])
            k = k+1;
        Next[i] = k; 
    }
    /*for(int i = 0; i < len; i++){
        cout << Next[i] << " ";
    }*/
}
void KMP()
{
    int k = -1, slen = strlen(s), plen = strlen(p);
    cal_Next();
    for(int i = 0; i < slen; i++){
        while(k > -1&&p[k+1] != s[i]){
            k = Next[k];
        }
        if(p[k+1] == s[i])
            k = k+1;
        if(k == plen-1){
            k = Next[k];//可以重叠 
            cnt++; 
        }
    }
} 
int main()
{
    IO;
    cin >> n;
    while(n--){
        cnt=0;
        cin >> p >> s;
        KMP();
        cout << cnt << endl;
    }
    return 0;
} 

 hdu2087http://acm.hdu.edu.cn/showproblem.php?pid=2087

不能重叠

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cstdlib>
#include<cmath>
#include<vector>
#include<stack>
#include<queue>
#define lson l, m, rt<<1
#define rson m+1, r, rt<<1|1
#define IO ios::sync_with_stdio(false);cin.tie(0);
#define INF 1e9
#define MAXN 500010
const int MOD=1e9+7;
typedef long long ll;
using namespace std;
int n, Next[10010], cnt;
char s[1000010], p[10010];
void cal_Next()
{
    int k = -1, len = strlen(p);
    Next[0] = -1;
    for(int i = 1; i < len; i++){
        while(k > -1&&p[k+1] != p[i]){
            k = Next[k];//核心 
        }
        if(p[k+1] == p[i])
            k = k+1;
        Next[i] = k; 
    }
    /*for(int i = 0; i < len; i++){
        cout << Next[i] << " ";
    }*/
}
void KMP()
{
    int k = -1, slen = strlen(s), plen = strlen(p);
    cal_Next();
    for(int i = 0; i < slen; i++){
        while(k > -1&&p[k+1] != s[i]){
            k = Next[k];
        }
        if(p[k+1] == s[i])
            k = k+1;
        if(k == plen-1){
            k = -1;//不重叠 
            cnt++; 
        }
    }
} 
int main()
{
    IO;
    while(cin >> s){
        if(s[0] == '#')
            break;
        cin >> p;
        cnt=0;
        KMP();
        cout << cnt << endl;
    }
    return 0;
}