[Konjac konjac cultivation Plan] [VIJOS1002] [NOIP2005] cross the river

Source: Internet
Author: User

Description

given a line number, the starting point is 0, and some of the integer points on the axis have pebbles. Each interval that can be moved is [s,t]. The minimum number of stones to tread when reaching or exceeding L.

Input

the first line of input has a positive integer L (1 <= l <= 10^9).

The second line has three positive integers S,t,m,M represents the number of stones on the bridge, of which 1 <= S <= T <= 10,1 <= M <=.

The third line has M different positive integers represent the position of the M -stone on the axis ( the data guarantees no stones at 0 and L of the bridge ). All adjacent integers are separated by a space.

Output

The output includes only an integer that represents the minimum number of stones to tread.

Sample Input

10

2 3 5

2 3 5) 6 7

Sample Output

2

Solution

The DP equationis listed first , F[i] indicates the minimum number of stones to step on when I arrive , then F[i]=min (F[i-k]) (s<=k<=t).

and then found that the data range is 10^9, so need to shape pressure.

It can be found that if there is a stone in k+s*t and k+s*t+x (k>=0,x>0), if there is a scheme to cross the k+s*t, it canalso be crossed k+s* T+x.

specific proof when the S*t as T -S Add, easy to pass can reach k+s*t, can also reach k+s*t+x.

So it's just a matter of narrowing the distance over s*t to s*t .

`1#include <cmath>2#include <ctime>3#include <queue>4#include <stack>5#include <cstdio>6#include <vector>7#include <cstring>8#include <cstdlib>9#include <iostream>Ten#include <algorithm> One #defineM 101 A #defineL 20001 - using namespacestd; - inta[m],f[l],l,m,s,t; the BOOLSto[l]; -Inlinevoidinit () { -scanf"%d%d%d%d",&l,&s,&t,&m); -      for(intI=1; i<=m;i++) +scanf"%d",&a[i]); -Sort (A +1, A +1+m); +     if(s==t) { A          for(intI=1; i<=m;i++) at             if(! (a[i]%s) &&a[i]<=l) -f[0]++; -printf"%d\n", f[0]); -         return; -     } -      for(intI=1, d;i<=m;i++){ in         if(a[i]-a[i-1]>s*t) { -d=a[i]-a[i-1]-s*T; to              for(intj=i;j<=m;j++) +a[j]-=D; -         } thesto[a[i]]=true; *     } \$     if(l-a[m]>s*t) l=a[m]+s*T;Panax NotoginsengFill (f+1, f+1+l,m); -      for(inti=s;i<=l;i++){ thef[i]=f[i-s]; +          for(intJ=min (t,i); j>=s;j--) AF[i]=min (f[i],f[i-j]); thef[i]+=Sto[i]; +     } -printf"%d\n", F[l]); \$ } \$ intMain () { -Freopen ("river.in","R", stdin); -Freopen ("River.out","W", stdout); the init (); - fclose (stdin);Wuyi fclose (stdout); the     return 0; -}`

[Konjac konjac cultivation Plan] [VIJOS1002] [NOIP2005] cross the river

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