View Compilation Error

0_0_4335804_20754.cpp: In function `void pushdown(int)':
0_0_4335804_20754.cpp:69: error: `swap' undeclared (first use this function)
0_0_4335804_20754.cpp:69: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_4335804_20754.cpp: In function `void update(int, int, int)':
0_0_4335804_20754.cpp:86: error: `swap' undeclared (first use this function)