<span style="font-family:宋体;">图</span><span>1</span><span style="font-family:宋体;">：在母串中第</span><span>pos</span><span style="font-family:宋体;">个位置定位子串的算法</span><span></span>

<span><img alt="" width="510" height="205" src="http://tk.hustoj.com:80/upload/pimg1746_2.jpg" /></span>

<span style="font-family:宋体;">图</span><span>2</span><span style="font-family:宋体;">：从母串中第</span><span>pos</span><span style="font-family:宋体;">个位置获得长度为</span><span>len</span><span style="font-family:宋体;">的子串</span><span></span>

Solution C

#include <stdio.h>
int main(){
	int ii,i,j,k,flag;
	char str[100],sub[100];
//	freopen("1.txt","r",stdin);
	while (scanf("%s %s",str,sub)!=EOF)
	{
	
			for (j=0;str[j];j++)
			{
				if (sub[0]!=str[j])
				{
					continue;
				}else{
					k=j;
					i=0;
					flag=1;
					while (sub[i]&&str[k])
					{
						if (sub[i++]!=str[k++])
						{
							flag=0;
							break;
						}
					}
					if (flag)
					{
						if (!sub[i])
						{
							printf("%d\n",j+1);
							break;
						}
						if (!str[k])
						{
							j=k;
						}
					}
				}
		}
		if (!str[j])
		{
			printf("0\n");
		}
			
	}
//	fclose(stdin);
	return 0;
}

Solution C++

#include <stdio.h>
#include <string.h>

typedef char SString[100];
typedef int Status;
#define OK 1
#define ERROR 0

int StrLength(SString str){
	// 计算字符串的长度
	return strlen(str+1);
}

int StrCompare(SString str1, SString str2){
	// 比较两个字符串是否相等
	return !strcmp(str1+1, str2+1);
}

Status SubString(SString &Sub, SString S, int pos, int len) {
   // 算法4.3
   // 用Sub返回串S的第pos个字符起长度为len的子串。
   // 其中，1≤pos≤StrLength(S)且0≤len≤StrLength(S)-pos+1。
   int i;
   if (pos < 1 || pos > S[0] || len < 0 || len > S[0]-pos+1)
      return ERROR;
   for(i=1; i<=len; i++)
      Sub[i] = S[pos+i-1];
   Sub[len+1] = '\0';
   return OK;
} // SubString

int Index(SString S, SString T, int pos) {  // 算法4.1
   // T为非空串。若主串S中第pos个字符之后存在与T相等的子串，
   // 则返回第一个这样的子串在S中的位置，否则返回0
   int n,m,i;
   SString sub;
   if (pos > 0) {
      n = StrLength(S);
      m = StrLength(T);
      i = pos;
      while (i <= n-m+1) {
         SubString(sub, S, i, m);
         if (StrCompare(sub,T) == 0) ++i;
         else return i;
      } // while
   } // if
   return 0;
}

int main(){

	SString strA, subStr;	// 定义存储母串和子串的存储空间
	while(scanf("%s%s", strA+1, subStr+1) != EOF){	// 读取母串与子串
		printf("%d\n", Index(strA, subStr, 1));
	}

	return 0;
}

Solution Java

import java.util.*;
public class Main 
{
	public static void main(String[] args)
	{
		Scanner cin = new Scanner(System.in);
		String s1,s2;
		int n;
		while(cin.hasNext())
		{
			s1=cin.next();
			s2=cin.next();
			System.out.println(s1.indexOf(s2, 0)+1);
		}
		cin.close();
	}
}