F. Omega Numbers

this is my solution

for every element I iterate over different value of omega and iterate over different gcd of element and form each gcd I iterate over different multiples of gcd ..why it didnot get tle ?? it passed in 1218 ms.

How many ways to draw non-crossing lines (chords) between any subset of n <= 1e6 points on a circle, such that:

1 - Lines do not cross each other.

2 - Multiple lines may share a common endpoint (i.e., chords can share points).

3 - Some points may remain unused

int n;
vector<int>p, v;
int get(int a){
    return p[a] = (a==p[a]) ? a : get(p[a]);   
}
void unin(int a, int b){
    a = get(a);
    b = get(b);
    p[a] = b;
}

I implemented  this code when I was solving problems about Dsu in section Edu..now if I used path compression in get function but I donot Consider the samllest set and larget set in union ..can the comlexity reach O(N)

I get The idea of Problem D Today But I was getting WA and I did not know where is the wrong.. After the contest I discovered that my map donot do sorting to vector of string in it ...

why ???

map<char, vector<string>>mp;
for(auto i:mp){
    sort(i.second.begin(), i.second.end());
}

this is the test that my friend give me after contest:

1

1

D

9H 4H

How I can Find smallest Odd Prime factor of n n<=10^18

we have test cases 10^5

[D. Min Cost String](https://mirror.codeforces.com/contest/1511/problem/D)
I have an intutive approach but I want to know why he work??I want proof??
suppose we will use the first 5 character..
first: we will put the the characters at even position like that:
`a_b_c_d_e_a_b_c_d_e_a_b_c_d_e`

the the first k chars at even positions we will shift them by 1
and put  the shifted chars at odd positions like that 
`a_b_c_d_e`
`_b_c_d_e_a`
`abbccddeea`

the second k chars at even positions we will shift them by 2
and put  the shifted chars at odd positions like that 
`a_b_c_d_e`
`_c_d_e_a_b`
`acbdcedaeb`

you can say that the char at odd position j is equal to the char at position (j-1) plus number of shifts like s[j]=(s[j-1]+sh)%k;
sorry for my bad english...can someone prove it??

here's my submision

hi..
how I can find the problems that based on grid and construct them, manipulate..
like these problems 
1- G.(A/B Matrix)->https://mirror.codeforces.com/contest/1360/problem/G
2-D.(Grid-00100)->https://mirror.codeforces.com/problemset/problem/1371/D
I solved them and I got AC..but I want more and more ..I cannot find it in tags of codeforces..
sorry for my bad English

WA test 5?? https://ideone.com/DeStN9?fbclid=IwAR3h5Wv-07TzZXZ1toX7IHhcpoHbS0z3d-_2TsXND0otmkxiuHjdeY86tcU http://www.usaco.org/index.php?page=viewproblem2&cpid=916&fbclid=IwAR1-fumL-ZfDaGs1zcgLCdPo5oHlKxk6QKhwVN8LPvw_XK1jaaot-801LeE