KMP—HDU2594

比较基础的kmp算法题目

代码如下：

#include <iostream>
#include <cstring>
#include <cstdio>
using namespace std;
const int maxn = 50010;

char a[maxn+5];
char b[maxn+5];
char t[maxn+5];
char p[maxn+5];
int f[maxn+5];
char res[maxn+5];
void getFail()
{
    int len = strlen(p);
    f[0] = 0, f[1] = 0;
    int j = 0;
    for(int i = 1; i < len; i++) {
        j = f[i];
        if(j && p[j]!=p[i]) j = f[j];
        f[i+1] = p[j]==p[i] ? j+1 : 0;
    }
}

void match() {
    getFail();
    int len = strlen(t);
    int j = 0;
    for(int i = 0; i < len; i++) {
        while(j && t[i]!=p[j]) j = f[j];
        if(t[i]==p[j]) j++;
    }
    int idx = 0;
    for(int i = j-1; i >= 0; i--) {
        res[idx++] = p[i];
    }
    res[idx] = '\0';
    if(j==0) printf("0\n");
    else printf("%s %d\n", res, j);
}

int main()
{
    while(gets(a) && a[0]) {
        gets(b);
        int lena = strlen(a);
        int idx = 0;
        for(int i = lena-1; i >= 0; i--) {
            t[idx++] = a[i];
        }
        t[idx] = '\0';
        idx = 0;
        int lenb = strlen(b);
        for(int i = lenb-1; i >= 0; i--) {
            p[idx++] = b[i];
        }
        p[idx] = '\0';
        match();
    }
    return 0;
}