map<char,int> A;

A['a']=1,A['b']=2,A['c']=3,A[' ']=1;

A['d']=1,A['e']=2,A['f']=3;

A['g']=1,A['h']=2,A['i']=3;

A['j']=1,A['k']=2,A['l']=3;

A['m']=1,A['n']=2,A['o']=3;

A['p']=1,A['q']=2,A['r']=3,A['s']=4;

A['t']=1,A['u']=2,A['v']=3;

A['w']=1,A['x']=2,A['y']=3,A['z']=4;

使用map建好表之後只要將每個按鍵需要按的次數加起來即可。