Hopscotch POJ

给出一个5*5的数组，问能组成多少个不重复的六位组合

参考别人的博客得出的思路，利用stl中set的去重性

#include <cstdio>#include <algorithm>#include <set>#include <string>using namespace std;int mp[10][10];int tx[4]={0,1,0,-1};int ty[4]={1,0,-1,0};string ss;set<string> s; void dfs(int x,int y,int c) {if (c==5) {s.insert(ss);return;}for (int i=0;i<4;i++) {int xx=x+tx[i];int yy=y+ty[i];if (xx<0 || yy<0 || xx>=5 || yy>=5) continue;ss.push_back(mp[xx][yy]+'0');dfs(xx,yy,c+1);ss.resize(ss.size()-1);     //pop_back通不过c++的编译}return;}int main(){for (int i=0;i<5;i++) {for (int j=0;j<5;j++) scanf ("%d",&mp[i][j]);}for (int i=0;i<5;i++) {for (int j=0;j<5;j++) {ss=mp[i][j]+'0';dfs(i,j,0);}} printf ("%d\n",s.size());return 0;   }