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.jpg)
第1行：两个用空格隔开的整数N和E.
第2到2N行：每行有2E-I个字符，表示地图．
每行有一个表示方向的字母和一个表示要开几个十字路口的数字表示．
Sample Input
.jpg)
题解：一开始没仔细看题的时候以为是灌水法。。。可是后来想到貌似不见得就一条路径，而且题目中貌似说了要最短路径
不知道正解是啥，反正我还是一如既往的逗比——以地图上每个+符号（S、E也算）为节点，建立无向图，然后就成了求最短路径的问题了，然后就是神烦的边spfa边记录路径了，话说这道水题居然写了我好久唉TT
1 /************************************************************** 2 Problem: 1687 3 User: HansBug 4 Language: Pascal 5 Result: Accepted 6 Time:32 ms 7 Memory:2600 kb 8 ****************************************************************/ 9 10 const dir:array[1..4] of char=(‘N‘,‘E‘,‘S‘,‘W‘); 11 type 12 point=^node; 13 node=record 14 g,w,q:longint; 15 next:point; 16 end; 17 var 18 i,j,k,l,m,n,x0,y0,x1,y1,x,y,f,r,s,t,v:longint; 19 map:array[0..100,0..100] of longint; 20 a:array[0..10000] of point; 21 b,c,g:array[0..10000] of longint; 22 d:array[0..100000] of longint; 23 e,h:array[0..100000,1..2] of longint; 24 ch:char; 25 p:point; 26 procedure add(x,y,z,t:longint); 27 var p:point; 28 begin 29 new(p);p^.g:=y;p^.w:=z; 30 p^.q:=t;p^.next:=a[x];a[x]:=p; 31 end; 32 begin 33 fillchar(map,sizeof(map),0); 34 readln(n,m); 35 n:=n*2-1;m:=m*2-1; 36 for i:=1 to n do 37 begin 38 for j:=1 to m do 39 begin 40 read(ch); 41 case upcase(ch) of 42 ‘S‘:begin 43 map[i,j]:=-1; 44 x0:=i;y0:=j; 45 end; 46 ‘E‘:begin 47 map[i,j]:=-1; 48 x1:=i;y1:=j; 49 end; 50 ‘.‘:map[i,j]:=0; 51 ‘-‘:map[i,j]:=-2; 52 ‘|‘:map[i,j]:=-3; 53 ‘+‘:map[i,j]:=-1; 54 end; 55 end; 56 readln; 57 end; 58 s:=0;t:=0;v:=0; 59 for i:=1 to n do 60 for j:=1 to m do 61 if map[i,j]=-1 then 62 begin 63 inc(v); 64 map[i,j]:=v; 65 if (x0=i) and (y0=j) then s:=v; 66 if (x1=i) and (y1=j) then t:=v; 67 end; 68 for i:=1 to n do 69 for j:=1 to m do 70 begin 71 if map[i-1,j]<>0 then 72 begin 73 x:=i-1;y:=j; 74 while map[x,y]=-3 do dec(x); 75 if map[x,y]>0 then add(map[i,j],map[x,y],1,1); 76 end; 77 if map[i+1,j]<>0 then 78 begin 79 x:=i+1;y:=j; 80 while map[x,y]=-3 do inc(x); 81 if map[x,y]>0 then add(map[i,j],map[x,y],1,3); 82 end; 83 if map[i,j-1]<>0 then 84 begin 85 x:=i;y:=j-1; 86 while map[x,y]=-2 do dec(y); 87 if map[x,y]>0 then add(map[i,j],map[x,y],1,4); 88 end; 89 if map[i,j+1]<>0 then 90 begin 91 x:=i;y:=j+1; 92 while map[x,y]=-2 do inc(y); 93 if map[x,y]>0 then add(map[i,j],map[x,y],1,2); 94 end; 95 end; 96 fillchar(g,sizeof(g),0); 97 fillchar(c,sizeof(c),0); 98 fillchar(b,sizeof(b),0); 99 fillchar(e,sizeof(e),0); 100 d[1]:=s;f:=1;r:=2;g[s]:=1;c[s]:=1; 101 while f<r do 102 begin 103 p:=a[d[f]]; 104 while p<>nil do 105 begin 106 if (c[p^.g]=0) or ((c[p^.g]>0) and (c[p^.g]>(c[d[f]]+p^.w))) then 107 begin 108 c[p^.g]:=c[d[f]]+p^.w; 109 b[p^.g]:=d[f]; 110 e[p^.g,1]:=p^.q;e[p^.g,2]:=p^.w; 111 if g[p^.g]=0 then 112 begin 113 g[p^.g]:=1; 114 d[r]:=p^.g; 115 inc(r); 116 end; 117 end; 118 p:=p^.next; 119 end; 120 inc(f); 121 g[d[f]]:=0; 122 end; 123 for i:=1 to v do dec(c[i]); 124 i:=0;fillchar(h,sizeof(h),0); 125 while t<>0 do 126 begin 127 inc(i); 128 h[i,1]:=e[t,1]; 129 h[i,2]:=e[t,2]; 130 t:=b[t]; 131 end; 132 v:=i-1; 133 for i:=1 to v div 2 do 134 begin 135 j:=h[i,1];h[i,1]:=h[v+1-i,1];h[v+1-i,1]:=j; 136 j:=h[i,2];h[i,2]:=h[v+1-i,2];h[v+1-i,2]:=j; 137 end; 138 inc(v);h[v,1]:=5;h[v,2]:=0; 139 j:=h[1,1];k:=h[1,2]; 140 for i:=2 to v do 141 begin 142 if h[i,1]=j then 143 k:=k+h[i,2] 144 else 145 begin 146 writeln(dir[j],‘ ‘,k); 147 k:=h[i,2];j:=h[i,1]; 148 end; 149 end; 150 readln; 151 end.
1687: [Usaco2005 Open]Navigating the City 城市交通
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原文地址：http://www.cnblogs.com/HansBug/p/4414550.html
