View Compilation Error

0_0_17154471_11523.cpp:18:2: error: default argument missing for parameter 3 of 'qnode::qnode(int, int, std::string)'
  qnode(int _v=0, int _d=0, string _color):v(_v),d(_d),color(_color){}
  ^
0_0_17154471_11523.cpp: In function 'void Dijkstra(int, int)':
0_0_17154471_11523.cpp:60:35: error: 'std::string' has no member named 'add'
    string clr = E[tmp.v][i].color.add()//添加颜色
                                   ^
0_0_17154471_11523.cpp:95:1: error: expected ',' or ';' at end of input
 }
 ^
0_0_17154471_11523.cpp:95:1: error: expected '}' at end of input
0_0_17154471_11523.cpp:95:1: error: expected '}' at end of input
0_0_17154471_11523.cpp:95:1: error: expected '}' at end of input