View Compilation Error

0_0_1714178_20738.cpp: In function `int main()':
0_0_1714178_20738.cpp:38: error: no match for 'operator=' in 'map[u] = 0'
0_0_1714178_20738.cpp:8: note: candidates are: word& word::operator=(const word&)
0_0_1714178_20738.cpp:73: error: no match for 'operator!=' in 'map[u] != 0'
0_0_1714178_20738.cpp:74: error: cannot convert `word' to `word*' in initialization