0_0_33015850_2017.cpp: In function 'int main()': 0_0_33015850_2017.cpp:43:23: error: 'sort' was not declared in this scope sort(r,r+n,cmp); ^ 0_0_33015850_2017.cpp:45:34: error: 'memset' was not declared in this scope memset(sum,0, sizeof(sum)); ^