### GlebsHP's blog

By GlebsHP, history, 2 years ago, ,

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 » 2 years ago, # |   0 Auto comment: topic has been updated by GlebsHP (previous revision, new revision, compare).
 » 2 years ago, # | ← Rev. 2 →   0 In the problem C I used a map to store previous queries to pass on the 100th test case. It worked, lol
•  » » 2 years ago, # ^ | ← Rev. 2 →   0 and main program?Are you using the is_sorted() function in stl?upd:sorry I'm bit naive
•  » » » 2 years ago, # ^ |   0 No, actually I precomputed the answer as said in the problem explanation.But my algorithm runs on O(k*m), Because it checks every column, it's pretty easy to repeat queries just to slow it down. Só I used a map to store previous queries. Here is a link: 24986527.
•  » » » » 2 years ago, # ^ |   +1 you are so clever.
•  » » » » 2 years ago, # ^ |   0 I saw your solution, the key here is using "pref" dynamic programming, not the map. No need to store the previous queries, I can pass all test without map and faster two times yours. 25166547
•  » » » » » 2 years ago, # ^ |   +1 What I meant was that I didn't need to quite do what the editorial said and it worked. Later I did what the editorial explained.cheers
•  » » » » » » 2 years ago, # ^ |   0 :) But they are similar!
•  » » » » 2 years ago, # ^ |   0 nice....haha...
•  » » 2 years ago, # ^ |   0 Seems distinct queries are very needed
•  » » 2 years ago, # ^ |   0 i saw ur comment and did the same thing :)
 » 2 years ago, # | ← Rev. 3 →   +3 There may be a mistake in prob E's solution.ans[i] += opt[i].height; should be ans[i] += r[i].height;opt.back() should be opt.top()Is it right?
•  » » 2 years ago, # ^ |   0 Yes, fixed now. Thanks you!
 » 2 years ago, # |   0 for problem E can't we use modified longest increasing sub-sequence in O(nlgn) ?
•  » » 2 years ago, # ^ | ← Rev. 2 →   0 i did something similar to LIS, but in the end it's not so far from the solution proposed above #include #include #include using namespace std; int II(){int n;scanf("%d",&n);return n;} void II(int n){printf("%d\n",n);} typedef long long ll; void LL(ll n){printf("%lld\n",n);} typedef pair il; struct ring_t { int inner,outer,height; bool operator<(ring_t b) { if(b.outer==outer)return inner>b.inner; return outer>b.outer; } }; #define MAXN 100000 ring_t V[MAXN]; ring_t *vend=V; int main() { int N=II(); set dp; while(N--)*vend++={II(),II(),II()}; ll H=0; sort(V,vend); for(ring_t *x=V;xinner,x->outer,x->height); ll myH=0; { auto it=dp.lower_bound({x->outer,-1}); if(it!=dp.begin()) { it--; myH=it->second; } } myH+=x->height; H=max(H,myH); { auto r=dp.insert({x->inner,myH}); if(r.second) { auto it=r.first; auto prv=it;prv++; while(prv!=dp.end()&&it->second>=prv->second) { dp.erase(prv); prv=it;prv++; } } } //for(auto y:dp)printf("[%d|%d] ",y.first,y.second);putchar(10); } LL(H); } 
 » 2 years ago, # |   0 Should the dynamic programming recursion be ans(i) = maxj < i, bj > aians(j) + hi instead of what you wrote?
•  » » 2 years ago, # ^ |   0 Sorry, I misunderstood your notation.
 » 2 years ago, # |   0
 » 2 years ago, # |   0 I think there is a mistake in 777C. It's supposed to be "such that the table is not decreasing in COLUMN j" right? Thanks for the editorial!
 » 2 years ago, # | ← Rev. 2 →   0 In problem C, should be a[i, j] <= a[i + 1, j] instead of a[i, j] < a[i + 1, j].
 » 2 years ago, # |   +19 When CF round #403 begins?
 » 2 years ago, # |   0 I see that there is a binary search tag for problem C. Did anyone solve this problem using binary search? Please enlighten me on how to use binary search for this problem.
•  » » 2 years ago, # ^ |   0 If you just store the indexes which are greater than the next number in an adjacency list for each column. Then for each query you could apply binary search within that range and see if no such element exists even for one column, then Yes. But there seems to be some kind of optimization that I have missed. Plus, the approach is way slower than that in the editorial. This might helpPlease let me know if I'm wrong.
 » 2 years ago, # |   0 I am unable to understand the tutorial for problem C. Can anybody please explain the tutorial in a more easy way. I am new to DP. Thank you.
 » 2 years ago, # |   0 Here are two submissions for problem D.2634862726348633These two submissions contain exactly the same code. Yet, I didn't use the same compiler. The first one got TLE, and the second one got Accepted. I would be thankful if anybody could explain me why.
 » 17 months ago, # |   0 Problem E (777E - Hanoi Factory):Could someone please explain the second approach described in the tutorial?I'm failing to understand how/why it should work with stack.
•  » » 17 months ago, # ^ |   0 If someone could provide a link to a complete solution which uses the approach, it could possibly help as well.
•  » » 16 months ago, # ^ |   0 I was able to understand an approach behind this submission: 33027274.It is also stack-based,although I'm not sure it uses the same idea(because I'm still not sure I understand the tutorial's idea).
 » 10 months ago, # |   0 can someone provide me dp solution for B