/in/foo.cc: In function 'int main()':
/in/foo.cc:18:5: error: 'memset' was not declared in this scope
     memset(f,-INF,sizeof(f));//初始时候，只有f[0][0]=0是合法的f[0][j]都不合法，要设为负无穷  
     ^~~~~~
/in/foo.cc:18:5: note: suggested alternative: 'wmemset'
     memset(f,-INF,sizeof(f));//初始时候，只有f[0][0]=0是合法的f[0][j]都不合法，要设为负无穷  
     ^~~~~~
     wmemset