#include <iostream>

using namespace std;

int main()
{
    string s, s1, s2;
    char c;
    while (cin >> c, c != ',') s += c;
    while (cin >> c, c != ',') s1 += c;
    while (cin >> c) s2 += c;

    if (s.size() < s1.size() || s.size() < s2.size()) puts ("-1");
    else
    {
        int l = 0;
        while (l + s1.size() <= s.size())
        {
            int k = 0;
            while (k < s1.size())
            {
                if (s[l + k] != s1[k]) break;
                k ++ ;
            }
            if (k == s1.size()) break;
            l ++ ;
        }

        int j = s.size() - s2.size();
        while (j >= 0)
        {
            int k = 0;
            while (k < s2.size())
            {
                if (s[j + k] != s2[k]) break;
                k ++ ;
            }
            if (k == s2.size()) break;
            j -- ;
        }
        l += s1.size() - 1;
        if (j <= l) puts("-1");
        else printf("%d\n", j - l - 1);
    }



    return 0;
}

for循环写法

#include <iostream>

using namespace std;

int main()
{
    string s, s1, s2;
    char c;
    while (cin >> c, c != ',') s += c;
    while (cin >> c, c != ',') s1 += c;
    while (cin >> c) s2 += c;

    if (s.size() < s1.size() || s.size() < s2.size()) puts("-1");
    else 
    {
        int l = 0;
        for (; l + s1.size() < s.size(); l ++ )
        {
            int k = 0;
            for (; k < s1.size(); k ++ )
            if (s[l + k] != s1[k]) break;
            if (k == s1.size()) break;
        }
        int j = s.size() - s2.size();
        for (; j >= 0; j --)
        {
            int k = 0;
            for (; k < s2.size(); k ++ )
            if (s[j + k] != s2[k]) break;
            if (k == s2.size()) break;
        }

        l += s1.size() - 1;
        if (j < l) puts("-1");
        else printf("%d\n", j - l - 1);
    }

    return 0;
}

简洁写法(看起来干净些)

#include <iostream>

using namespace std;

int main()
{
    string a, b, c;
    char d;
    while (cin >> d, d != ',') a += d;
    while (cin >> d, d != ',') b += d;
    while (cin >> d) c += d;

    if (b.size() > a.size() || c.size() > a.size()) puts("-1");

    else
    {
        int i = 0; 
        for (; i + b.size() < a.size(); i ++ ) 
        {
            int j = 0;
            while (j < b.size() && a[i + j] == b[j]) j ++ ;
            if (j == b.size()) break;
        }
        int k = a.size() - c.size();    
        for (; k > 0; k -- ) 
        {
            int n = 0;
            while (n < c.size() && a[k + n] == c[n]) n ++ ;
            if (n == c.size()) break;
        }

        i += b.size() - 1;
        if (k < i) puts("-1");
        else cout << k - i - 1 << endl;
    }

    return 0;
}