POJ 2965

第一次使用位运算

 

其中两个重要的函数，可以加入代码库

// get dig from t, right xthint getDig(int t, int x){return t>>(x-1)&1;}void changeDig(int& t, int x){t=t^(1<<(x-1));} 

 

用BFS搜，加状态压缩，最多2^16个状态

 

 #include <iostream>#define maxn 65540#define F(i,a,b) for (int i=a;i<=b;i++)#include <vector>using namespace std;// get dig from t, right xthint getDig(int t, int x){return t>>(x-1)&1;}void changeDig(int& t, int x){t=t^(1<<(x-1));}int Q[maxn], mk[maxn], f[maxn], l[maxn], r[maxn], now, last, start;void bfs(){//initnow=0, last=0;Q[++last]=start;mk[start]=true;while (true){int s=Q[++now];int temp=s;F(i,1,4){F(j,1,4){int temp=s;//ith rowF(k,0,3)changeDig(temp, 20-4*i-k);F(k,0,3)changeDig(temp, 5-j+k*4);changeDig(temp, 17-4*(i-1)-j );if (!mk[temp]){Q[++last]=temp;mk[temp]=true;f[last]=now;l[last]=i;r[last]=j;if (temp==( (1<<16)-1) ){vector<int> v;int k=last, total=0;while (f[k]!=0){v.push_back(k);k=f[k];total++;}cout << total << endl;vector<int>::iterator it=v.end()-1;cout << l[*it] << " " << r[*it] << endl;while (it!=v.begin() ){it--;cout << l[*it] << " " << r[*it] << endl;}return;}}}}}}int main(){//freopen ("in.txt", "r" ,stdin);char ch;start=0;for (int i=1;i<=16;i++){//incin >> ch;if (i!=1)start<<=1;if (ch=='-')start++;}bfs();return 0;}