"Hdoj" 4455 substrings

Source: Internet
Author: User

The 5000ms time limit is quite long. The algorithm is DP.
The idea is to find the results of ANS[1..N], and then query is easy to do. The question is how DP?
Consider:
1 1 2 3 4 4 5w=1:7, 7 = 1 * 7
w=2:10,10 = | {1,1}|+| {1,2}|+| {2,3}|+| {3,4}|+| {4,4}|+| {4,5}|=1+2+2+2+1+2=10
W=3:12, 12 = | {1, 1, 2}|+| {1, 2, 3}|+| {2, 3, 4}|+| {3, 4, 5}|+| {4, 4, 5}|
...
To observe how w=3 is calculated on the basis of w=2, the first need to subtract | {4,5}|, and then consider whether 2,3,4,5,5 (the last number of each collection) is distinct.

Therefore, O (n^2) is solvable. However, the range of n is 1e6 and must be timed out.
So, simplify the idea and divide it into three parts.
1. ans[n-1];
2. In the number of post-K ([1..N]), the number of distinct can be obtained within O (n).
3. Consider a[w. N] If the number is increased by 1, you can think of a different idea.
Consider 1 1 2 3 4 4 5 in 3, because 3 is not previously present, so w=[1..4], this 3 will provide an increment of 1.
Consider 1 3 2, 4 4 5, because there is a 3, two spacing of 2, so w=[1..2], this 3 will provide an increment of 1.
A delta array is visible, and two O (n) loops can be determined for W=[1..N], what is the Delta Delta?
At the end, you can synthesize it.

1 /*4455*/2#include <iostream>3#include <string>4#include <map>5#include <queue>6#include <Set>7#include <stack>8#include <vector>9#include <deque>Ten#include <algorithm> One#include <cstdio> A#include <cmath> -#include <ctime> -#include <cstring> the#include <climits> -#include <cctype> -#include <cassert> -#include <functional> +#include <iterator> -#include <iomanip> + using namespacestd; A //#pragma COMMENT (linker, "/stack:102400000,1024000") at  - #defineSTI set<int> - #defineStpii Set<pair<int, int> > - #defineMpii map<int,int> - #defineVI vector<int> - #definePII pair<int,int> in #defineVpii vector<pair<int,int> > - #defineRep (I, A, n) for (int i=a;i<n;++i) to #definePer (i, a, n) for (int i=n-1;i>=a;--i) + #defineCLR Clear - #definePB Push_back the #defineMP Make_pair * #defineFIR First $ #defineSEC SecondPanax Notoginseng #defineAll (x) (x). Begin (), (x). End () - #defineSZ (x) ((int) (x). Size ()) the #defineLson L, Mid, rt<<1 + #defineRson mid+1, R, rt<<1|1 A  the Const intMAXN = 1e6+5; + intA[MAXN], B[MAXN]; - intPRE[MAXN]; $ __int64 DELTA[MAXN], ANS[MAXN]; $ BOOLMARK[MAXN]; -  - intMain () { theIos::sync_with_stdio (false); - #ifndef Online_judgeWuyiFreopen ("data.in","R", stdin); theFreopen ("Data.out","W", stdout); -     #endif Wu      -     intN, q, x; About     intl, TMP; $     intI, J, K; -      -      while(SCANF ("%d", &n)!=eof &&N) { -          for(i=1; i<=n; ++i) { Ascanf"%d", &a[i]); +++A[i]; the         } -memset (Delta,0,sizeof(delta)); $memset (PRE,0,sizeof(pre)); thememset (Mark,0,sizeof(Mark)); the          the         //handle last I number the          for(i=n,j=1; I>0; --i,++j) { -             if(Mark[a[i]]) { inB[J] = b[j-1]; the}Else { theB[J] = b[j-1]+1; AboutMark[a[i]] =true; the             } the         } the         //Handle Pre +          for(i=1; i<=n; ++i) { -L = i-Pre[a[i]]; the             //[1, l]++Bayidelta[1]++; thedelta[l+1]--; thePre[a[i]] =i; -         } -ans[1] =N; the          for(i=2; i<=n; ++i) { theDelta[i] + = delta[i-1]; theAns[i] = ans[i-1] + delta[i]-b[i-1]; the         } -          thescanf"%d", &q); the          while(q--) { thescanf"%d", &x);94printf"%i64d\n", ans[x]); the         } the     } the     98 #ifndef Online_judge Aboutprintf"Time =%d.\n", (int) clock ()); -     #endif101     102     return 0;103}

"Hdoj" 4455 substrings

Contact Us

The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion; products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the content of the page makes you feel confusing, please write us an email, we will handle the problem within 5 days after receiving your email.

If you find any instances of plagiarism from the community, please send an email to: info-contact@alibabacloud.com and provide relevant evidence. A staff member will contact you within 5 working days.

A Free Trial That Lets You Build Big!

Start building with 50+ products and up to 12 months usage for Elastic Compute Service

  • Sales Support

    1 on 1 presale consultation

  • After-Sales Support

    24/7 Technical Support 6 Free Tickets per Quarter Faster Response

  • Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.