DouKaku?

--- 4.cpp.old    Thu May 22 16:17:00 2008
+++ 4.cpp.new    Thu May 22 16:16:47 2008
@@ -72,9 +72,7 @@
         std::vector<std::vector<long> >(max_x,
             std::vector<long>(m + 1, std::numeric_limits<long>::max())));
 
-    dp.front().swap(
-        std::vector<std::vector<long> >(max_x,
-            std::vector<long>(m + 1, 0)));
+    dp[0] = std::vector<std::vector<long> >(max_x, std::vector<long>(m + 1, 0));
 
     REPE(y1, 0, n) REP(x1, 0, max_x) if (slip[y1][x1] >= 0) // source
     {