Hdu 6071 Lazy Running【同余最短路】
来源:互联网 发布:淘宝 企业店铺 编辑:程序博客网 时间:2024/06/05 23:01
Lazy Running
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 524288/524288 K (Java/Others)Total Submission(s): 927 Accepted Submission(s): 381
Problem Description
In HDU, you have to run along the campus for 24 times, or you will fail in PE. According to the rule, you must keep your speed, and your running distance should not be less thanK meters.
There are4 checkpoints in the campus, indexed as p1,p2,p3 and p4 . Every time you pass a checkpoint, you should swipe your card, then the distance between this checkpoint and the last checkpoint you passed will be added to your total distance.
The system regards these4 checkpoints as a circle. When you are at checkpoint pi , you can just run to pi−1 or pi+1 (p1 is also next to p4 ). You can run more distance between two adjacent checkpoints, but only the distance saved at the system will be counted.
Checkpointp2 is the nearest to the dormitory, Little Q always starts and ends running at this checkpoint. Please write a program to help Little Q find the shortest path whose total distance is not less thanK .
There are
The system regards these
Checkpoint
Input
The first line of the input contains an integer T(1≤T≤15) , denoting the number of test cases.
In each test case, there are5 integers K,d1,2,d2,3,d3,4,d4,1(1≤K≤1018,1≤d≤30000) , denoting the required distance and the distance between every two adjacent checkpoints.
In each test case, there are
Output
For each test case, print a single line containing an integer, denoting the minimum distance.
Sample Input
12000 600 650 535 380
Sample Output
2165HintThe best path is 2-1-4-3-2.
题目大意:
现在有4个点,我们一开始在点2处 ,我们希望最终也回到点2处 ,问我们怎样走,使得总路径和大于等于K并且最小。
思路:
我们知道,我们可以选以2为起点,1作为另一个点(或者是3的话也是相同的道理),使得我们的主人公一直徘徊在这条路径上,那么我们最终的Ans,可以表示为2*W(1,2)+Len这里Len的长度明显在区间:【0,2*W(1,2)】之间,那么我们就去跑一个同余的最短路即可。
那么我们SPFA跑最短路,处理出数组Dist【i】【Len】表示,从2出发,到点i处,长度%2*W(1,2)为Len的最短路。
那么对于结果,我们枚举区间【0,2*W(1,2)】的值作为Len,然后向上去添加 2*W(1,2)即可。
对于Dist【2】【i】,我们考虑:
如果Dist【2】【i】>=K,那么更新ans=min(ans,Dist【2】【i】);
否则我们设定Ned=K-Dist【2】【i】,表示缺少的路径长度,我们向上去添加2*W(1,2)即可,添加的长度为:Ned/2*W(1,2)*(2*W(1,2))+Ned%(2*W(1,2))==0?0:2*W(1,2)。
其内容不难理解。
注意初始化数组和INF要足够大,就没有别的什么坑点了。
Ac代码:
#include<stdio.h>#include<string.h>#include<algorithm>#include<iostream>#include<queue>using namespace std;#define ll __int64const ll INF=2e18;struct node{ int u; ll len;} now,nex;ll mod;ll mp[5][5];ll vis[5][70050];ll dist[5][70050];void SPFA(){ queue<node>s; memset(vis,0,sizeof(vis)); for(int j=1; j<=4; j++) { for(int k=0; k<=70000; k++) { dist[j][k]=INF; } } dist[2][0]=0; now.u=2,now.len=0; s.push(now); while(!s.empty()) { now=s.front(); // vis[now.u][now.len%mod]=0; s.pop(); for(int v=1; v<=4; v++) { if(mp[now.u][v]!=INF) { nex.u=v; nex.len=now.len+mp[now.u][v]; if(dist[v][nex.len%mod]>now.len+mp[now.u][v]) { dist[v][nex.len%mod]=now.len+mp[now.u][v]; if(vis[v][nex.len%mod]==0) { vis[v][nex.len%mod]=1; s.push(nex); } } } } }}int main(){ int t; scanf("%d",&t); while(t--) { ll K,a,b,c,d; scanf("%I64d%I64d%I64d%I64d%I64d",&K,&a,&b,&c,&d); for(int i=1; i<=4; i++) { for(int j=1; j<=4; j++) { mp[i][j]=INF; } } mp[1][2]=mp[2][1]=a; mp[2][3]=mp[3][2]=b; mp[3][4]=mp[4][3]=c; mp[4][1]=mp[1][4]=d; mod=2*mp[1][2]; SPFA(); ll ans=INF; for(int i = 0; i < mod; i++) { if(dist[2][i]>=K) { ans=min(ans,dist[2][i]); } else { ll ned=K-dist[2][i]; ll tmp; if(ned%mod==0)tmp=0; else tmp=mod; ans=min(ans,dist[2][i]+ned/mod*mod+tmp); } } printf("%I64d\n",ans); }}
阅读全文
2 0
- HDU 6071 Lazy Running(同余+最短路)
- HDU 6071 Lazy Running(同余最短路)
- HDU 6071 Lazy Running 同余 + 最短路
- HDU 6071 Lazy Running(同余最短路)
- Hdu 6071 Lazy Running【同余最短路】
- HDU 6071 Lazy Running(模同余最短路)
- hdu 6071 Lazy Running(spfa+同余最短路)
- 2017多校第4场 HDU 6071 Lazy Running 同余最短路
- 2017多校四 1005题 hdu 6071 Lazy Running 同余类 最短路
- hdu6071-最短路&思维&多校4&同余-Lazy Running
- Hdu-6071 Lazy Running(trick最短路)
- 2017年多校赛第四场 1005 Lazy Running(同余最短路)
- HDU6071Lazy Running(同余最短路)
- 同余最短路
- 同余最短路
- HDU6071 Lazy Running【最短路】
- HDU6071-Lazy Running 最短路+思维
- POJ6071 Lazy Running(最短路)
- 初见openssl
- 数据库编程题
- 使用call方法自定义接受者来调用方法
- Camera---基础属性及注意点
- 【程序笔记】第一期-深究bool类型
- Hdu 6071 Lazy Running【同余最短路】
- 多标签分类(multilabel classification )
- 【巨坑】recyclerview在适配器更新后布局混乱
- 执行scala
- 操作系统实例Linux探索
- 【分析】Ceph系统架构与基本概念
- Docker——监控
- 2017百度之星资格赛1002:度度熊的王国战略(最小割)
- 【英语】maintext2-Emotional Mastery译文