HDU - 1401 Solitaire
从起点和终点分别搜，找是否存在8步内共同经过的点
这样就可以把暴力的时间复杂度开根号
1 #include<map> 2 #include<queue> 3 #include<cstdio> 4 #include<cstring> 5 #include<algorithm> 6 using namespace std; 7 int n,m,cnt,ans,tim,d1,d2,d3; 8 int dx[4]={1,0,-1,0}; 9 int dy[4]={0,1,0,-1}; 10 int mp[11][11]; 11 struct node{ 12 int x[4]; 13 int y[4]; 14 }st,ed,fla; 15 long long make_order(node a){ 16 int tmp[4]={0,0,0,0}; 17 long long ret=0;long long mul=100; 18 for(int i=0;i<4;i++){ 19 tmp[i]=(a.x[i]-1)*8+a.y[i]; 20 } 21 sort(tmp,tmp+4); 22 for(int i=3;i>=0;i--){ 23 ret=1ll*ret*mul+tmp[i]; 24 } 25 return ret; 26 } 27 bool bfs(){ 28 queue<node>que1; 29 queue<node>que2; 30 map<long long,int>dis1; 31 map<long long,int>dis2; 32 que1.push(st); 33 que2.push(ed); 34 dis1[make_order(st)]=0;dis2[make_order(ed)]=0; 35 while(1){ 36 node s=que1.front(); 37 que1.pop(); 38 if(dis1[make_order(s)]>4)break; 39 for(int i=0;i<4;i++){ 40 mp[s.x[i]][s.y[i]]=1; 41 } 42 for(int i=0;i<4;i++){ 43 for(int j=0;j<4;j++){ 44 int fl=0; 45 int xx=s.x[i]+dx[j]; 46 int yy=s.y[i]+dy[j]; 47 while(mp[xx][yy]){ 48 xx+=dx[j]; 49 yy+=dy[j]; 50 fl++; 51 } 52 if(xx>8||xx<1||yy>8||yy<1)continue; 53 node to=s;to.x[i]=xx,to.y[i]=yy; 54 if(dis1.find(make_order(to))==dis1.end() && fl<=1){ 55 dis1[make_order(to)]=dis1[make_order(s)]+1; 56 que1.push(to); 57 if(dis2.find(make_order(to))!=dis2.end()){ 58 tim=dis1[make_order(to)]+dis2[make_order(to)]; 59 if(tim<=8)return true; 60 } 61 } 62 } 63 } 64 for(int i=0;i<4;i++){ 65 mp[s.x[i]][s.y[i]]=0; 66 } 67 s=que2.front(); 68 que2.pop(); 69 if(dis2[make_order(s)]>4)break; 70 for(int i=0;i<4;i++){ 71 mp[s.x[i]][s.y[i]]=1; 72 } 73 for(int i=0;i<4;i++){ 74 for(int j=0;j<4;j++){ 75 int fl=0; 76 int xx=s.x[i]+dx[j]; 77 int yy=s.y[i]+dy[j]; 78 while(mp[xx][yy]){ 79 xx+=dx[j]; 80 yy+=dy[j]; 81 fl++; 82 } 83 if(xx>8||xx<1||yy>8||yy<1)continue; 84 node to=s;to.x[i]=xx,to.y[i]=yy; 85 if(dis2.find(make_order(to))==dis2.end() && fl<=1){ 86 dis2[make_order(to)]=dis2[make_order(s)]+1; 87 que2.push(to); 88 if(dis1.find(make_order(to))!=dis1.end()){ 89 tim=dis1[make_order(to)]+dis2[make_order(to)]; 90 if(tim<=8)return true; 91 } 92 } 93 } 94 } 95 for(int i=0;i<4;i++){ 96 mp[s.x[i]][s.y[i]]=0; 97 } 98 } 99 return false; 100 } 101 int main(){ 102 while(scanf("%d%d",&st.x[0],&st.y[0])>0){ 103 for(int i=1;i<4;i++){ 104 scanf("%d%d",&st.x[i],&st.y[i]); 105 } 106 for(int i=0;i<4;i++){ 107 scanf("%d%d",&ed.x[i],&ed.y[i]); 108 } 109 if(make_order(st)==make_order(ed)){ 110 printf("YES\n"); 111 continue; 112 } 113 if(bfs()){ 114 printf("YES\n"); 115 } 116 else printf("NO\n"); 117 } 118 return 0; 119 }
