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先对整幅图进行二分图染色,再跑一遍匈牙利算法。如果最大匹配数=点数*2,那么输出WIN。
对于任何一个非必须在最大匹配上的点,即为所求的点。
1 Program Test375num2; 2 type arr=record 3 u,v,next:longint; 4 end; 5 const dx:array[1..4] of longint=(0,0,-1,1); 6 dy:array[1..4] of longint=(1,-1,0,0); 7 maxn=100008; 8 maxm=maxn*4; 9 var map:array[0..108,0..108] of longint; 10 cl:array[0..maxn] of longint; 11 eg:array[0..maxm] of arr; 12 last:array[0..maxn] of longint; 13 l,r,f:array[0..maxn] of longint; 14 pd:array[0..maxn] of boolean; 15 i,j,m,n,num,sum,x:longint; 16 ch:char; 17 procedure dfs(i,j,w:longint); 18 var k,x,y:longint; 19 begin 20 cl[map[i,j]]:=w; 21 for k:=1 to 4 do 22 begin 23 x:=i+dx[k]; y:=j+dy[k]; 24 if (map[x,y]>0) and (cl[map[x,y]]=0) then 25 dfs(x,y,3-w); 26 end; 27 end; 28 procedure add(u,v:longint); 29 begin 30 inc(sum); 31 eg[sum].u:=u; 32 eg[sum].v:=v; 33 eg[sum].next:=last[u]; 34 last[u]:=sum; 35 end; 36 procedure put(i,j:longint); 37 var k,x,y:longint; 38 begin 39 for k:=1 to 4 do 40 begin 41 x:=i+dx[k]; y:=j+dy[k]; 42 if (map[x,y]>0) then add(map[i,j],map[x,y]); 43 end; 44 end; 45 function Hungarian(u:longint):boolean; 46 var i,v:longint; 47 begin 48 i:=last[u]; 49 while i<>0 do 50 begin 51 v:=eg[i].v; 52 if not pd[v] then 53 begin 54 pd[v]:=true; 55 if (l[v]=0) or Hungarian(l[v]) then 56 begin 57 r[u]:=v; 58 l[v]:=u; 59 exit(true); 60 end; 61 end; 62 i:=eg[i].next; 63 end; 64 exit(false); 65 end; 66 procedure dfsl(u:longint); 67 var i,v:longint; 68 begin 69 f[u]:=2; 70 i:=last[u]; 71 while i<>0 do 72 begin 73 v:=eg[i].v; 74 if f[v]=0 then 75 begin 76 f[v]:=1; 77 if f[l[v]]=0 then dfsl(l[v]); 78 end; 79 i:=eg[i].next; 80 end; 81 end; 82 83 procedure dfsr(u:longint); 84 var i,v:longint; 85 begin 86 f[u]:=2; 87 i:=last[u]; 88 while i<>0 do 89 begin 90 v:=eg[i].v; 91 if f[v]=0 then 92 begin 93 f[v]:=1; 94 if f[r[v]]=0 then dfsr(r[v]); 95 end; 96 i:=eg[i].next; 97 end; 98 end; 99 begin 100 readln(m,n); 101 num:=0; sum:=0; 102 for i:=1 to m do 103 begin 104 for j:=1 to n do 105 begin 106 read(ch); 107 if ch=‘.‘ then 108 begin 109 map[i,j]:=(i-1)*n+j; 110 inc(num); 111 end 112 else map[i,j]:=-1; 113 end; 114 readln; 115 end; 116 for i:=1 to m do 117 for j:=1 to n do 118 if (map[i,j]>0) and (cl[map[i,j]]=0) then 119 dfs(i,j,1); 120 for i:=1 to m do 121 for j:=1 to n do 122 if map[i,j]>0 then put(i,j); 123 124 fillchar(l,sizeof(l),0); 125 fillchar(r,sizeof(r),0); 126 sum:=0; 127 for i:=1 to m*n do 128 if cl[i]=1 then 129 begin 130 fillchar(pd,sizeof(pd),false); 131 if Hungarian(i) then inc(sum); 132 end; 133 if sum*2=num then 134 begin 135 writeln(‘LOSE‘); 136 halt; 137 end; 138 writeln(‘WIN‘); 139 fillchar(f,sizeof(f),0); 140 for i:=1 to m*n do 141 if (cl[i]>0) and (f[i]=0) and (l[i]=0) and (r[i]=0) then 142 if cl[i]=1 then dfsl(i) else dfsr(i); 143 for i:= 1 to m do 144 for j:=1 to n do 145 begin 146 x:=(i-1)*m+j; 147 if f[x]=2 then writeln(i,‘ ‘,j); 148 end; 149 end.
ps:好像没有LOSE的点 ←_ ←
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原文地址:http://www.cnblogs.com/rpSebastian/p/4178795.html