Create 1321_sshaohua.cpp

From http://poj.org/showmessage?message_id=353467

POJ/1321_sshaohua.cpp

@@ -0,0 +1,47 @@
+#include <iostream>
+#include <cstdio>
+#include <algorithm>
+#include <cmath>
+#include <cstring>
+#include <queue>
+#include <stack>
+//notice the '#' can be placed.
+using namespace std;
+const int MAXN = 10;
+
+int n, m;
+int ans = 0;
+char my_map[MAXN][MAXN];
+bool vis_row[MAXN];     //vis_row[i], i row is visited.
+bool vis_col[MAXN];     //vis_col[j], j col is visited.
+
+bool judge(int x, int y){
+    if(x<0 || x>=n || y<0 || y>=n || my_map[x][y]!='#') return false;
+    if(vis_row[x] || vis_col[y]) return false;
+    return true;
+}
+
+void DFS(int x, int y, int step){
+    //int xx, yy;
+    if(step == m) {ans++; return;}
+    for(int i=x; i<n; i++)
+    for(int j=0; j<n; j++){
+        if(judge(i, j)){
+            vis_row[i] = vis_col[j] = true;
+            DFS(i, j, step+1);
+            vis_row[i] = vis_col[j] = false;
+        }
+    }
+}
+
+int main(){
+    while(scanf("%d%d", &n, &m) && n!=-1 && m!=-1){
+        ans = 0;
+        memset(vis_row, false, sizeof(vis_row));
+        memset(vis_col, false, sizeof(vis_col));
+        for(int i=0; i<n; i++) scanf("%s", my_map[i]);
+        DFS(0, 0, 0);
+        printf("%d\n", ans);
+    }
+    return 0;
+}