HDU1711 Number Sequence KMP

欢迎访问~原文出处——博客园-zhouzhendong

去博客园看该题解


题目传送门 - HDU1711


题意概括

  给T组数据,每组有长度为n和m的母串和模式串。判断模式串是否是母串的子串,如果是输出最先匹配完成的位置,否则输出-1.


题解

  KMP裸题。


代码

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
#include <cstring>
#include <algorithm>
#include <cstdio>
#include <cstdlib>
#include <cmath>
using namespace std;
const int N=1000005,M=10005;
bool isd(char ch){
    return '0'<=ch&&ch<='9';
}
void read(int &x){
    int f=1;
    x=0;
    char ch=getchar();
    while (!isd(ch)&&ch!='-')
        ch=getchar();
    if (ch=='-')
        f=-1,ch=getchar();
    while (isd(ch))
        x=x*10+ch-48,ch=getchar();
    x*=f;
}
int T,n,m,a[N],b[M],Next[M];
int main(){
    read(T);
    while (T--){
        read(n),read(m);
        for (int i=0;i<n;i++)
            read(a[i]);
        for (int i=0;i<m;i++)
            read(b[i]);
        memset(Next,0,sizeof Next);
        int k=0;
        for (int i=1;i<m;i++){
            while (k&&b[k]!=b[i])
                k=Next[k-1];
            if (b[k]==b[i])
                k++;
            Next[i]=k;
        }
        int ans=-1;
        k=0;
        for (int i=0;i<n;i++){
            while (k&&b[k]!=a[i])
                k=Next[k-1];
            if (b[k]==a[i])
                k++;
            if (k==m){
                ans=i-m+2;
                break;
            }
        }
        printf("%d\n",ans);
    }
    return 0;
}

  

posted @   zzd233  阅读(245)  评论(0编辑  收藏  举报

点击右上角即可分享
微信分享提示