View Compilation Error

0_0_29583269_19859.cpp: In function 'void init()':
0_0_29583269_19859.cpp:51:26: error: no matching function for call to 'std::vector<int>::swap(std::vector<int>)'
   a[i].swap(vector<int>());
                          ^
0_0_29583269_19859.cpp:51:26: note: candidate is:
In file included from GCC4.9.2/x86_64-w64-mingw32/include/c++/vector:64:0,
                 from 0_0_29583269_19859.cpp:4:
GCC4.9.2/x86_64-w64-mingw32/include/c++/bits/stl_vector.h:1194:7: note: void std::vector<_Tp, _Alloc>::swap(std::vector<_Tp, _Alloc>&) [with _Tp = int; _Alloc = std::allocator<int>]
       swap(vector& __x)
       ^
GCC4.9.2/x86_64-w64-mingw32/include/c++/bits/stl_vector.h:1194:7: note:   no known conversion for argument 1 from 'std::vector<int>' to 'std::vector<int>&'