Blogs.txt

Tricks-
http://codeforces.com/blog/entry/15643
https://codeforces.com/blog/entry/75456
In questions related to strings when n can 10^5 one possible way to approach could be character wise i.e. rep(i,0,26){rep(j,0,n){}}
eg- https://codeforces.com/contest/519/problem/D

suppose a 2-D matix is given as 1-D form as ROW MAJOR. if an elements index is i in 1-D then in 2-D
col number=i%col
row number=i/col

DP
https://apps.topcoder.com/forums/?module=Thread&start=0&threadID=697369
https://codeforces.com/blog/entry/43256
https://codeforces.com/blog/entry/45068

https://codeforces.com/blog/entry/53925 ==>Nisiyama_Suzune's blog
he/she covers advanced maths topics

https://codeforces.com/blog/entry/77298=> slope trick

https://codeforces.com/blog/entry/15296 ==>Adamant's dynamic connectivity

https://codeforces.com/blog/entry/45223 ==>SOS Dynamic Programming

https://www.quora.com/q/threadsiiithyderabad?sort=top => Lalit Kundu's Blog

http://codeforces.com/blog/entry/70467 => ouuan segment tree template

//struct with initialisation...
struct node{
    ll p0,p1,p2,p3;
    node(ll one,ll two,ll three,ll four):
        p0{one},p1{two},p2{three},p3{four} {}
    ll v[4]={p0,p1,p2,p3};
};

comparator => bool func(a,b);
if you want to sort ascending => return b<a;
if you want to sort descending => return a<b;

in general i feel like the order is in which the arguments appear is assumed to be the correct order, then you should return true if that ordering is correct and false if thats not the case.

writing comparators for set in cpp
struct cmp{
    bool operator()(int a,int b){
        return a>b;
    }
};
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order statistics tree
https://codeforces.com/blog/entry/11080
policy based data structures

#include <ext/pb_ds/assoc_container.hpp>
#define ok(x)          order_of_key(x)
#define fo(x)          find_by_order(x)
using namespace __gnu_pbds;
typedef tree<int, null_type, less_equal<int>, rb_tree_tag, tree_order_statistics_node_update> os;
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Seg Tree- 
https://codeforces.com/blog/entry/44478?#comment-290116
https://codeforces.com/blog/entry/44478?#comment-290057
https://codeforces.com/blog/entry/15890
interesting problems that i've solved with seg trees...
number of smaller elements in left side.
kth smaller number.
deleting elements from array cses-1749

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Perseg Tree-
https://discuss.codechef.com/t/distnum2-editorial/12566

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Rectangular Grid Walking
https://brilliant.org/wiki/rectangular-grid-walk-no-restriction/
------------------------------------------------------------------------

KMP-booth's algorithm
The Booth's algorithm uses a modified version of the KMP preprocessing function to find the lexicographically minimal string rotation. The failure function is progressively calculated as the string is rotated.

https://en.wikipedia.org/wiki/Knuth%E2%80%93Morris%E2%80%93Pratt_algorithm#Variants

int rot(string s){
    s+=s;
    int n=s.length();
    int f[n];
    rep(i,0,n)f[i]=-1;
    int k=0;
    rep(j,1,n){
        int sj=s[j];
        int i=f[j-k-1];
        while(i!=-1 && sj!=s[k+i+1]){
            if(sj<s[k+i+1])k=j-i-1;
            i=f[i];
        }
        if(sj!=s[k+i+1]){
            if(sj<s[k])k=j;
            f[j-k]=-1;
        }
        else{
            f[j-k]=i+1;
        }

    }
    return k;
}

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Implementation of LONGEST PALINDROMIC SUBSTRING(MANACHER'S)
https://www.geeksforgeeks.org/manachers-algorithm-linear-time-longest-palindromic-substring-part-4/

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PLAYLISTS
https://www.youtube.com/playlist?list=PLi0ZM-RCX5nvImim3_ilsdLOtDDkOWt-X
https://www.youtube.com/playlist?list=PLixpXjrHOw3YDrcGY1Y6yCAAyuFsmKNZK
https://www.youtube.com/playlist?list=PLi0ZM-RCX5nsTc2Z6woHr5qoF6n3b-thO
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representation of a number as diff of squares :-https://qr.ae/pNvqR2

IMPORTANT FACT 
upper bound for number of divisors for n => n^(1/3)
upper bound for number of primes less than n => n/(ln(n)-1.0836)
lower bound for number of primes less than n => n/ln(n)

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MO's algorithm on Trees
https://codeforces.com/blog/entry/68271
https://codeforces.com/blog/entry/43230

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Rerooting Technique
https://codeforces.com/blog/entry/76150
https://codeforces.com/blog/entry/68142
https://codeforces.com/blog/entry/53265