### web_developer's blog

By web_developer, history, 14 months ago,

Hello Codeforces, I need help with this problem

My sol. -> I've written recursive solution and it gives TLE on tc 20

Now, I want to optimize this... How can I? Plz help.

Thanks!!

• 0

By web_developer, history, 14 months ago,

Hello codeforces, I was solving this problem and I ended up with below solution, but this solution doesn't seem to work on test case 5, can you help me find where I've gone wrong and I don't want to see the editorial until I don't get my approach accepted. It's a simple bfs if you've got time to see it. Please help..I wasted so much time on this.

My approach: Firstly, I am making a bfs call from every node from 1 to n and finding their neighbours or second-neighbours and so on..so that minimum s towns having a different type of goods and for finding cost I am using a level array. Suppose I am starting bfs from node-2 then level of this node I am taking 0 and its neighbours level 1 and so on, so it gives me nearest s towns who has to produce a different type of goods and for answer, I am summing their cost. Hope you understood my approach.

Code

#include <bits/stdc++.h>
using namespace std;
#define N 100005
#define mod 1000000007

vector<bool> visited(N, false);
unordered_map<int, int> mp;
vector<int> goods(N);
vector<int> level(N, 0);
int ans=0;
int n, m, k, s;

void bfs(int node)
{
level[node]=0;
queue<int> q;
mp[goods[node]]++;
q.push(node);
while(!q.empty())
{
int tp=q.front();
q.pop();
visited[tp]=true;
if(mp.find(goods[tp])==mp.end())
{
ans+=level[tp];
mp[goods[tp]]++;
}
cout<<ans<<endl;
if(mp.size()==s)
{
cout<<ans<<" ";
return;
}
{
if(!visited[child])
{
q.push(child);
level[child]=level[tp]+1;
}
}
}
}

void solve()
{
cin>>n>>m>>k>>s;
rep(i, n)
{
cin>>goods[i];
}
rep(i, m)
{
int u, v;
cin>>u>>v;
u--, v--;
}
for(int i=0;i<n;i++)
{
ans=0;
mp.clear();
visited.clear();
visited=vector<bool>(N, false);
bfs(i);
}

}

signed main() {
// int t;cin>>t;while(t--)
solve();

return 0;
}


• -1

By web_developer, history, 14 months ago,

Hello codeforces! I want help with this Codeforces Round #497 (Div. 1) A problem...Even after looking at the editorial I didn't understand why it's answer is n-x. Please help me understand.....Thanks!!

• +2

By web_developer, history, 19 months ago,

Hello codeforces, I am the guy who spend more than 4 hours on the codeforces, But not solving problems, seeing Recent actions, standings, tourist's rating and other top coders most of the time. Someone would say, "It's rediculous", but I do. Any suggestions?

• +104

By web_developer, 19 months ago,

Hello Codeforces community, hope all of you are doing good. I wanna ask, is seeing editorial of any problem that you can't solve after spending 15 minutes on it a bad habit? Please make me know if someone of you did this and became better because I am considering it a bad habit and I am despondent about it. All the suggestions are appreciated. Thanks!