Bzoj 2038 small Z socks & MO team algorithm (not just a brute force ...)

Test instructions

Give a sequence, ask an interval, find the interval ... woc! Stick to the original question!

As a rambling person, little Z spends a lot of time every morning looking for a pair to wear from a bunch of colorful socks. Finally one day, little z can no longer endure this annoying to find socks process, so he decided to resign to fate ...
Specifically, small z to this n socks from 1 to n number, and then from the number L to R (L Although small z does not care about two socks is not a complete pair, even do not care about two socks whether a left and right, he is very concerned about the color of socks, after all, wearing two different color socks will be very embarrassing.
Your task is to tell Little Z how much he has the chance to draw two socks of the same color. Of course, Little Z wants this probability to be as high as possible, so he may ask multiple (l,r) to facilitate his choice.

Sol

Mo team Dafa Good, MO team is a way to fight violence, there is a very 6 of the paper, extremely clear and understandable ... (Dig a hole first, can't find ...)

Then directly on the code ... (first forget to open ll ....) It has been so many times ....

CODE:

　　

/*==========================================================================# last modified:2016-02-27 16:55# filename:2038.cpp# Description: ==========================================================================*/# Define me Acrossthesky #include <cstdio> #include <cmath> #include <ctime> #include <string> #inc (in)  Lude <cstring> #include <cstdlib> #include <iostream> #include <algorithm> #include <set> #include <map> #include <stack> #include <queue> #include <vector> #define LOWBIT (x) (x) & (-X ) #define for (I,A,B) for ((i) = (a);(i) <= (b);(i) + +) #define FORP (I,A,B) for (int i= (a); i<= (b); i++) #define FORM (i,a,b ) for (int i= (a); i>= (b); i--) #define LS (A, a) (((a) + (b)) << 1) #define RS (A, B) (((a) + (c)) >> 1) #define GETLC (a) ch[(a)][0] #define GETRC (a) ch[(a)][1] #define MAXN 100000 #define MAXM 100000 #define PI 3.1415926535898 #define _e 2.718281828459 #define INF 1070000000 using Namespace std; typedef long Long LL;  typedef unsigned long long ull;     Template<class t> inline void read (t& num) {bool start=false,neg=false;     char c;     num=0;         while ((C=getchar ())!=eof) {if (c== '-') start=neg=true;             else if (c>= ' 0 ' && c<= ' 9 ') {start=true;         num=num*10+c-' 0 ';     } else if (start) break; } if (neg) num=-num; }/*==================split line==================*/int l,r;struct query{int L,r,id,op;} Q[maxm];struct answer{ll X,tot;} Ans[maxm];bool CMP (const query &x,const query &y) {if (X.OP==Y.OP) return x.r<y.r; else return x.op<y.op;} ll GCD (ll A,ll b) {return b==0?a:gcd (b,a%b);} ll a[maxn],cnt[maxn];ll tmp=0;void Add (int i) {tmp+=cnt[a[i]]; cnt[a[i]]++;} void Remove (int i) {cnt[a[i]]--;tmp-=cnt[a[i]];} void Solve (int l,int r,int ID) {while (l>l) {remove (L); l++;} while (l<l) {l--; add (l);} while (r<r) {remove (R); r--;} while (r>r) {r++; add (r);} Ans[id].x=tmp;//forp (i,l,r) Ans[id]. x+= (cnt[i]* (cnt[i-1])/2);} int main () {int n,m; read (n); read (m); int Sz=trunc (sqrt (n));//num=n/sz+n%sz?0:1; Forp (i,1,n) read (A[i]); Forp (i,1,m) {read (Q[I].L); Read (Q[I].R); q[i].id=i;q[i].op=q[i].l/sz+ (q[i].l%sz?1:0);} Sort (q+1,q+1+m,cmp); Tmp=0,l=q[1].l,r=q[1].r;ll num=r-l+1; Forp (i,l,r) Add (i); ans[q[1].id].x=tmp; ans[q[1].id].tot=num* (num-1)/2; Forp (i,2,m) {num=q[i].r-q[i].l+1;//if (i==1) l=q[i].l,r=q[i].r;ans[q[i].id].tot=num* (num-1)/2;solve (Q[I].L,Q[I].R , q[i].id);} Forp (i,1,m) {if (ans[i].x==0) {printf ("0/1\n"); continue;} ll T=GCD (Ans[i].x,ans[i].tot);p rintf ("%lld/%lld\n", ans[i].x/t,ans[i].tot/t);}}

Bzoj 2038 small Z socks & MO team algorithm (not just a brute force ...)