From f920a379567b0c21e0be73cb8ecc964973063adb Mon Sep 17 00:00:00 2001
From: Kirito <1362050620@qq.com>
Date: Thu, 1 Sep 2016 20:22:43 +0800
Subject: [PATCH] Create 2531_martin31hao.cpp

From http://blog.csdn.net/martin31hao/article/details/8098302
---
 POJ/2531_martin31hao.cpp | 45 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)
 create mode 100644 POJ/2531_martin31hao.cpp

diff --git a/POJ/2531_martin31hao.cpp b/POJ/2531_martin31hao.cpp
new file mode 100644
index 0000000..91cdb70
--- /dev/null
+++ b/POJ/2531_martin31hao.cpp
@@ -0,0 +1,45 @@
+#include<cstdio>
+#include<cstring>
+using namespace std;
+
+const int maxn = 30;
+int n, ans;
+int a[maxn][maxn];
+int dep[maxn];
+
+void dfs(int id, int data)
+{
+    dep[id] = 1;
+    int tmp = data;
+    for(int i = 1; i <= n; i ++)
+    {
+        if(dep[i] == 0)
+            tmp += a[i][id];
+        else
+            tmp -= a[i][id];
+    }
+    if(ans < tmp)
+        ans = tmp;
+    for(int i = id + 1; i <= n; i ++)
+    {
+        if(tmp > data)
+        {
+            dfs(i, tmp);
+            dep[i] = 0;
+        }
+    }
+}
+
+int main()
+{
+    while(~scanf("%d", &n))
+    {
+        for(int i = 1; i <= n; i ++)
+            for(int j = 1; j <= n; j ++)
+                scanf("%d", &a[i][j]);
+        memset(dep, 0, sizeof(dep));
+        ans = 0;
+        dfs(1, 0);
+        printf("%d\n", ans);
+    }
+}