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## Discussion of Problem 1060. Flip Game

WA #8
Posted by Faeton (Kyiv - Mohyla Academy) 29 Feb 2008 06:16
please, help me to find a bug, or give me some tests

Here is my code.

#include <iostream>
#include <vector>
#include <string>
#include <math.h>
#include <algorithm>
#include <string.h>
#include <stdio.h>

#define MAX_VAL 100

using namespace std;

int res = -1;

vector<int> mem;

void go(bool a[4][4],int cur) {
long hex = 0,step = 1;
for (int i = 0; i < 4; i++) {
for (int j = 0; j < 4; j++) {
if (a[i][j]==1) hex+=step;
step*=2;
}
}

if (hex==65535) {
if (cur<res||res==-1) res = cur;
return;
}

if (cur<mem[hex]) {
mem[hex] = cur;

int mov[4][2];

mov[0][0] = 1; mov[0][1] = 0;
mov[1][0] = -1;mov[1][1] = 0;
mov[2][0] = 0; mov[2][1] = 1;
mov[3][0] = 0; mov[3][1] = -1;

for (int x = 0; x < 4; x++) {
for (int y = 0; y < 4; y++) {
bool next[4][4];

for (int w1 = 0; w1 < 4; w1++) for (int w2 = 0; w2 < 4; w2++) next[w1][w2] = a[w1][w2];

for (int k = 0; k < 4; k++) {
int nx = x+mov[k][0],ny = y+mov[k][1];

if (nx>=0&&ny>=0&&nx<4&&ny<4)
next[nx][ny] = 1-next[nx][ny];// flip
}
next[x][y] = 1-next[x][y];

go(next,cur+1);
}
}
}
}

int main() {
bool a[4][4],f = true;

string s;
for (int i = 0; i < 4; i++) {
cin >> s;
for (int j = 0; j < 4; j++) {
if (s[j]=='w') a[i][j] = 0;
else {
a[i][j] = 1;
f = false;
}
}
}
if (f) {
cout << "0";
return 0;
}

for (long x = 0; x < 1<<16+1; x++) mem.push_back(MAX_VAL);

go(a,0);

if (res==-1) cout << "Impossible";
else cout << res;

return 0;
}