From 5090672f4360c077ce8c50a20684acd2f674bd07 Mon Sep 17 00:00:00 2001
From: Kirito <1362050620@qq.com>
Date: Tue, 13 Sep 2016 15:46:13 +0800
Subject: [PATCH] Create 2373_sunny606.cpp

From http://blog.csdn.net/sunny606/article/details/7854362
---
 POJ/2373_sunny606.cpp | 55 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)
 create mode 100644 POJ/2373_sunny606.cpp

diff --git a/POJ/2373_sunny606.cpp b/POJ/2373_sunny606.cpp
new file mode 100644
index 0000000..27a1ff4
--- /dev/null
+++ b/POJ/2373_sunny606.cpp
@@ -0,0 +1,55 @@
+#include<cstdio>
+#define L 1001000
+
+int a,b,n,l,inf,dp[L],queue[L],head,tail,size;
+
+void insert(int idx)
+{
+     tail++;
+     while(head<tail && dp[queue[tail-1]]>dp[idx]) tail--;
+     queue[tail]=idx;
+     while(idx-queue[head]>=size) head++;
+}
+
+int dpro(void)
+{
+     if(b<1) return -1;
+     dp[0]=0;
+     size=2*b+1;
+     head=0;
+     tail=-1;
+     
+     for(int i=a; i<=b; i++) if(dp[2*i]<=inf) dp[2*i]=1;     
+     int seg = 2*b-2*a;
+     for(int i=0; i<=seg; i+=2) insert(i);
+     
+     for(int i=2*b; i<=l; i+=2)
+     {
+         if(i-a*2>seg) insert(i-a*2);
+         while(i-queue[head]>=size) head++;
+         if (dp[i]<=inf) dp[i]=dp[queue[head]]+1;
+     }
+     
+     if(dp[l]>=inf) return -1;
+     else return dp[l];
+}
+
+int main()
+{
+    while (scanf("%d%d", &n, &l)!=EOF) {
+          
+          scanf("%d%d", &a, &b);
+          inf = (l/a)+9;
+          for(int i=0; i<=l; i++) dp[i]=inf;
+          
+          for(int i=0; i<n; i++) {
+                int s, e;  
+                scanf("%d%d", &s, &e);
+                for(int j=s+1; j<e; j++) dp[j] = inf+1;
+          }
+          
+          if(l&1==1) printf("-1\n");
+          else printf("%d\n", dpro());
+    }
+    return 0;
+}