View Compilation Error

0_0_38065059_23445.cpp: In function 'void KMP()':
0_0_38065059_23445.cpp:10:26: error: 'len' was not declared in this scope
     for (int i = 2; i <= len; ++i) {
                          ^
0_0_38065059_23445.cpp:12:45: error: invalid types '<unresolved overloaded function type>[int]' for array subscript
         s[i] == s[j + 1] ? kmp[i] = next[++j] : kmp[i] = j;
                                             ^