P1478 Tata pick Apples (upgrade version)

Tag: Sort ace means scan std CLU Node Air nbsp

Title Description

Another autumn, the Tautau apple tree has a fruit of n. Tata again ran to pick apples, this time she has a a-centimeter chair. When his hand is out of reach, he will stand on the chair and try again.

This time with the NOIp2005 popularization group first problem is different: Tata before moving stool, strength only left S. Of course, every time you pick an apple, you have to use a certain amount of effort. Tata want to know how many apples can be picked up before s<0.

Now known n apples to reach the height of the ground XI, chair height A, Tata hand straighten the maximum length B, Tata's remaining strength S, Tata pick an apple need the strength Yi, beg Tata can pick how many apples.

Input/output format Input Format:

Line 1th: Two number of apples N, strength s.

Line 2nd: The height of the two-digit chair A, Tata the maximum length of the hand straight B.

Line 3rd ~ Line 3+n-1: Two apples per row, Apple height XI, pick the strength that the Apple needs Yi.

output Format:

There is only one integer that represents the maximum number of apples the Tata can pick.

Input/Output sample Input Sample # #:

8 1520 130120 3150 2110 7180 150 8200 0140 3120 2

Sample # # of output:

4

Description

All data: n<=5000 a<=50 b<=200 s<=1000

      xi<=280  yi<=100

Title Description

Another autumn, the Tautau apple tree has a fruit of n. Tata again ran to pick apples, this time she has a a-centimeter chair. When his hand is out of reach, he will stand on the chair and try again.

This time with the NOIp2005 popularization group first problem is different: Tata before moving stool, strength only left S. Of course, every time you pick an apple, you have to use a certain amount of effort. Tata want to know how many apples can be picked up before s<0.

Now known n apples to reach the height of the ground XI, chair height A, Tata hand straighten the maximum length B, Tata's remaining strength S, Tata pick an apple need the strength Yi, beg Tata can pick how many apples.

Input/output format Input Format:

Line 1th: Two number of apples N, strength s.

Line 2nd: The height of the two-digit chair A, Tata the maximum length of the hand straight B.

Line 3rd ~ Line 3+n-1: Two apples per row, Apple height XI, pick the strength that the Apple needs Yi.

output Format:

There is only one integer that represents the maximum number of apples the Tata can pick.

Input/Output sample Input Sample # #:

8 1520 130120 3150 2110 7180 150 8200 0140 3120 2

Sample # # of output:

4

Description

All data: n<=5000 a<=50 b<=200 s<=1000

 xi<=280 yi<=100

The eldest brother above thought of using DP solution, but that equation I really did not understand ,,,
In fact, this question can be seen as a DP knapsack problem.
we have a physical strength s
for each can pick (height within the range) Apple we only pick or not pick two possibilities
so we're going to turn this problem into 01 knapsack problems.
state transition Equation
Dp[i][j]=max (dp[i-1][j],dp[i-1][j-a[i].v]+1);
By the way, in order to ensure the efficiency of the DP, I have all the apples in advance order, if the current Apple can not reach, indicating that the future of the apples are not enough, the direct exit will be
thus arises a problem, dp[n][maxt] is not necessarily the maximum value
The maximum value needs to be compared at each DP.
This is the only difference between this question and the 01 backpack.

1#include <iostream>2#include <cstdio>3#include <cstring>4#include <cmath>5#include <algorithm>6 using namespacestd;7 intN,maxt;8 intChair,hand;9 structnodeTen { One     intHigh ; A     intv; -}a[10001]; - intCompConstNode & A,ConstNode &b) the { -     if(a.high!=B.high) -     returna.high<B.high; -     Else  +     returna.v<B.V; - } + intdp[5001][1001]; A intans=0; at intMain () - { -scanf"%d%d%d%d",&n,&maxt,&chair,&hand); -Hand=hand+chair; -      for(intI=1; i<=n;i++) -scanf"%d%d",&a[i].high,&a[i].v); inSort (A +1, a+n+1, comp); -      for(intI=1; i<=n;i++) to     { +         if(hand>=A[i].high) -         { the              for(intj=0; j<=maxt;j++) *             { $                 if(a[i].v<=j)Panax NotoginsengDp[i][j]=max (dp[i-1][j],dp[i-1][j-a[i].v]+1); -                 Else thedp[i][j]=dp[i-1][j]; +ans=Max (ans,dp[i][j]); A             } the              +         } -         Else $          Break; $     } -printf"%d", ans); -     return 0; the}

P1478 Tata pick Apples (upgrade version)