Hdu5303 Delicious Apples Greedy

Source: Internet
Author: User

Topic Links:

HDU5303




Test instructions

There is a circular long road for L, warehouse at position 0,

There are n apple trees on the road, giving the location of each apple tree and the number of apples,

Ask for a basket of up to K apples to take the road all the apples back to the warehouse at least the distance needed to go




Problem Solving Ideas:

The road is circular, the fruit tree is divided into two parts, the left half of the circle is counted as part of the circle of the right half of the count is still part

For all apples based on the distance sort, with the idea of similar backpack, statistics left half, the right half with back and forth (the length must be less than a ring circumference) in the way of collecting the minimum distance that the apples need to go;

Finally consider the need to walk around the situation: the left more than K1 (<k) An apple, the right more than K2 (<k) an apple.

Infer the distance to take the K1 back and forth, and the distance to take the K2 and the size of the circumference of the long l to get the corresponding answer



Code:

#include <iostream> #include <cstdio> #include <cstring> #include <algorithm> #define LL Long Long#define maxn 100050using namespace Std;int dis[maxn],cnt;int ldis[maxn],rdis[maxn];int cnt1,cnt2; LL lsum[maxn],rsum[maxn];int cmp (int a,int b) {return a<b;}    int main () {//Freopen ("In.txt", "R", stdin);    int t,m,n,k,a,b,l;    scanf ("%d", &t);        while (t--) {scanf ("%d%d%d", &l,&m,&k);        cnt=cnt1=cnt2=0;            while (m--) {scanf ("%d%d", &a,&b);            if (a==0) continue;            if ((a<<1) <=l) for (int i=1;i<=b;i++) ldis[++cnt1]=a;        else for (int i=1;i<=b;i++) rdis[++cnt2]=l-a;        } sort (ldis+1,ldis+cnt1+1,cmp);        Sort (rdis+1,rdis+cnt2+1,cmp);                Cnt=cnt1+cnt2;            for (int i=1;i<=cnt1;i++)//left half by way of back and forth to get through if (i<=k) lsum[i]=ldis[i]; Else LSUM[I]=LDIS[I]+LSUM[I-K];            for (int i=1;i<=cnt2;i++)//Right half ... if (i<=k) rsum[i]=rdis[i];        else Rsum[i]=rdis[i]+rsum[i-k];                LL ans= (Lsum[cnt1]+rsum[cnt2]) <<1;        K=min (K,CNT);        int l_,r_;            for (int i=1;i<=cnt1&&i<=k;i++)//enumeration when walking around, the left half of the apple number {L_=cnt1-i,r_=max (0,cnt2-k+i);        Ans=min (ans,l+ ((lsum[l_]+rsum[r_)) <<1);    } printf ("%i64d\n", ans); } return 0;}


Hdu5303 Delicious Apples Greedy

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