[SCU 4497] Goozy game time (based on search time pruning)

SCU-4497

Given a n*n puzzle, ask to rearrange
Makes a block that is adjacent to each other on the same number of squares connected

It's rather disgusting.
I've just begun to move in the set by saving each line of work, and the result is a mle.

Later, a different idea, snake to find a block to connect
And then tried a few pruning, the effect is not ideal

Generate several sets of random data yourself
found that when the numbers are 0~3, compared to the concentration, run huge slow
It would have been 0~3 this repeatable probability was larger.
It is also possible to search the solution accordingly.
But without a solution, he would repeat the search, a waste of time.

Based on the above facts, I used a metaphysical pruning
I set a number of searches, and when the number of Dfs calls is too large, return as no solution
Probably WA three or four hair appearance, tried out the better parameters, 72ms ran over

Later I looked for the ZW chicory to ask the standard course, found that the calibration process is based on the above conditions for special pruning
But his pruning is more than my science.

#pragma COMMENT (linker, "/stack:102400000,102400000")#include <cstdio>#include <iostream>#include <cstdlib>#include <cstring>#include <algorithm>#include <cmath>#include <map>#include <set>#include <queue>using namespace STD;typedefpair<int,int> Pii;typedef Long LongLL;typedef unsigned Long LongULL;typedef DoubleDBL;typedef Long DoubleLdbl;#define MST (A, B) memset (A,b,sizeof (a) )#define CLR (a) MST (a,0)#define SQR (a) (a*a)Const intup=0, right=1, down=2, left=3;Const intTime=1e5;structnode{intn[4];};intN;node inpt[ -];intcnt[ -][ -];intmap[ -][ -];BOOLvis[ -];intNtime=0;intDfsint);voidGetcor (int,int&,int&);voidChangeint,int);BOOLCheckint);intMain () {#ifdef LOCALFreopen ("In.txt","R", stdin);//Freopen ("OUT.txt", "w", stdout);    #endif    intTscanf("%d", &t); for(intck=1; ck<=t; ck++) {ntime=0; CLR (VIS); CLR (CNT); CLR (MAP);scanf("%d", &n); for(intI=0; i<n*n; i++) for(intj=0; j<4; J + +) {scanf("%d", &inpt[i].n[j]);        cnt[j][inpt[i].n[j]]++; }if(Dfs (0) &&ntime<=time)puts("Possible");Else{puts("Impossible"); }//printf ("%lld\n", ntime);}return 0;}intDfsintStep) {if(++ntime>time)return 1;if(step==n*n)return 1; for(intI=0; i<n*n; i++) {if(Vis[i])Continue;intx, y; Getcor (Step,x,y);if(x && inpt[i].n[up]! = inpt[map[x-1][y]].n[down])Continue;if(x&1)        {if(y+1<n && inpt[i].n[right]! = inpt[map[x][y+1]].n[left])Continue; vis[i]=1; Map[x][y]=i;if(Dfs (step+1))return 1; map[x][y]=0; vis[i]=0; }Else{if(y && inpt[i].n[left]! = inpt[map[x][y-1]].n[right])Continue; vis[i]=1; Map[x][y]=i;if(Dfs (step+1))return 1; map[x][y]=0; vis[i]=0; }    }return 0;}voidGetcor (intStepint&x,int&y) {x=step/n;if(x&1) y=n-1-step%n;Elsey=step%n;}

[SCU 4497] Goozy game time (based on search time pruning)