From f21a2e1c48ff6cc8a3bc56cb40587b93cbfabc08 Mon Sep 17 00:00:00 2001
From: Kirito <1362050620@qq.com>
Date: Mon, 15 Aug 2016 15:06:02 +0800
Subject: [PATCH] Create 1128.cpp

---
 POJ/1128.cpp | 178 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 178 insertions(+)
 create mode 100644 POJ/1128.cpp

diff --git a/POJ/1128.cpp b/POJ/1128.cpp
new file mode 100644
index 0000000..c715fc9
--- /dev/null
+++ b/POJ/1128.cpp
@@ -0,0 +1,178 @@
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+
+#include <algorithm>
+using namespace std;
+
+#define INF 0x3f3f3f3f
+
+const int MAXH = 32;
+const int MAXW = 32;
+const int MAXCHARACTER = 26;
+char map[MAXH][MAXW];
+
+int up[MAXCHARACTER];
+int down[MAXCHARACTER];
+int left[MAXCHARACTER];
+int right[MAXCHARACTER];
+
+/// under[A][B]
+/// 表示字符B在A上面(under[A][B]==1) 或 未知(under[A][B]==0)
+int under[26][26];
+
+int indegree[26];
+int notes[26];
+int _GN;
+
+
+int ans[26];
+int visit[26];
+void DFS(int step)
+{
+    if(step==_GN)
+    {
+        for(int i=0; i<_GN; i++)
+        {
+            printf("%c",ans[i]+'A');
+        }
+        printf("\n");
+        return;
+    }
+    for(int j=0; j<_GN; j++)
+    {
+        if(!visit[notes[j]]&&indegree[notes[j]]==0)
+        {
+            for(int k=0;k<_GN;k++)
+            {
+                if(under[notes[j]][notes[k]])
+                {
+                    indegree[notes[k]]--;
+                }
+            }
+            visit[notes[j]]=1;
+            ans[step]=notes[j];
+            DFS(step+1);
+            /// Recover
+            visit[notes[j]]=0;
+            for(int k=0;k<_GN;k++)
+            {
+                if(under[notes[j]][notes[k]])
+                {
+                    indegree[notes[k]]++;
+                }
+            }
+        }
+    }
+}
+
+int main()
+{
+    int h,w;
+    while(scanf("%d %d%*c",&h,&w)==2)
+    {
+        memset(map,0,sizeof(map));
+        for(int i=1; i<=h; i++)
+        {
+            gets(&map[i][1]);
+        }
+        memset(up,0x3f,sizeof(up));
+        memset(down,0,sizeof(down));
+        memset(left,0x3f,sizeof(left));
+        memset(right,0,sizeof(right));
+        memset(under,0,sizeof(under));
+        memset(indegree,0,sizeof(indegree));
+        memset(notes,0,sizeof(notes));
+        memset(visit,0,sizeof(visit));
+        memset(ans,0,sizeof(ans));
+        for(int i=1; i<=h; i++)
+        {
+            for(int j=1; j<=w; j++)
+            {
+                if(map[i][j]=='.') continue;
+                int cc=map[i][j]-'A';
+                up[cc]=min(i,up[cc]);
+                down[cc]=max(i,down[cc]);
+                left[cc]=min(j,left[cc]);
+                right[cc]=max(j,right[cc]);
+            }
+        }
+        _GN=0;
+        for(int i=0; i<26; i++)
+        {
+            /// If a letter does not exist, skip it.
+            if(up[i]==INF) continue;
+            notes[_GN++]=i;
+            char c='A'+i;
+
+            /// Check the outline of the frame.
+            for(int col=left[i]; col<=right[i]; col++)
+            {
+                /// First Line
+                if(c!=map[up[i]][col])
+                {
+                    under[i][map[up[i]][col]-'A']=1;
+                }
+                /// Last Line
+                if(c!=map[down[i]][col])
+                {
+                    under[i][map[down[i]][col]-'A']=1;
+                }
+            }
+            for(int line=up[i]+1; line<=down[i]-1; line++)
+            {
+                /// First Col
+                if(c!=map[line][left[i]])
+                {
+                    under[i][map[line][left[i]]-'A']=1;
+                }
+                /// Last Col
+                if(c!=map[line][right[i]])
+                {
+                    under[i][map[line][right[i]]-'A']=1;
+                }
+            }
+        }
+
+        /// Graphical Sort
+
+        /// Calculate in-degree
+        for(int i=0; i<26; i++)
+        {
+            for(int j=0; j<26; j++)
+            {
+                if(under[i][j]!=0) indegree[j]++;
+            }
+        }
+
+        /**
+        //单拓扑排序(WA)
+        for(int i=0; i<_GN; i++)
+        {
+            for(int j=0; j<_GN; j++)
+            {
+                if(indegree[notes[j]]==0)
+                {
+                    indegree[notes[j]]--;
+                    printf("%c",notes[j]+'A');
+                    for(int k=0; k<_GN; k++)
+                    {
+                        if(under[notes[j]][notes[k]]==1)
+                        {
+                            indegree[notes[k]]--;
+                        }
+                    }
+                    break;
+                }
+            }
+        }
+        */
+
+        /// 全拓扑排序
+        DFS(0);
+    }
+
+    return 0;
+
+
+}