HDU 1711 Number Sequence kmp算法

题目:http://acm.hdu.edu.cn/showproblem.php?pid=1711

题意:给定两个数组,问能不能再第一个数组中匹配得到第二个数组,如果可以,那么输出最早匹配的起始位置,否则输出-1

思路:kmp直接匹配即可,中间写搓了一个地方,晕-_-||

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;

const int N = 10010;
int arr1[N*100], arr2[N], nt[N];
int n, m;
void getnt()
{
    int i = 0, j = -1;
    nt[0] = -1;
    while(i < m)
    {
        if(j == -1 || arr2[i] == arr2[j])
        {
            i++, j++;
            if(arr2[i] != arr2[j]) nt[i] = j;
            else nt[i] = nt[j];
        }
        else j = nt[j];
    }
}
int kmp()
{
    getnt();
    int i = 0, j = 0;
    while(i < n)
    {
        if(j == -1 || arr1[i] == arr2[j])
            i++, j++;
        else j = nt[j];
        if(j == m)
            return i - m + 1;
    }
    return -1;
}


int main()
{
    int t;
    scanf("%d", &t);
    while(t--)
    {
        scanf("%d%d", &n, &m);
        for(int i = 0; i < n; i++)
            scanf("%d", &arr1[i]);
        for(int i = 0; i < m; i++)
            scanf("%d", &arr2[i]);
        if(n < m) printf("-1\n");
        else printf("%d\n", kmp());
    }
    return 0;
}
    原文作者:KMP算法
    原文地址: https://blog.csdn.net/discreeter/article/details/52006104
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