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  • HDU 6071 同余最短路 spfa

    Lazy Running

    Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 524288/524288 K (Java/Others)
    Total Submission(s): 657    Accepted Submission(s): 284


    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 than K meters.

    There are 4 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 these 4 checkpoints as a circle. When you are at checkpoint pi, you can just run to pi1 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.




    Checkpoint p2 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 than K.
     
    Input
    The first line of the input contains an integer T(1T15), denoting the number of test cases.

    In each test case, there are 5 integers K,d1,2,d2,3,d3,4,d4,1(1K1018,1d30000), denoting the required distance and the distance between every two adjacent checkpoints.
     
    Output
    For each test case, print a single line containing an integer, denoting the minimum distance.
     
    Sample Input
    1 2000 600 650 535 380
     
    Sample Output
    2165
    Hint
    The best path is 2-1-4-3-2.
     
    Source
    题意:求从2点回到2点的路径距离和大于等与K的最小值
     1 #pragma comment(linker, "/STACK:102400000,102400000")
     2 #include <bits/stdc++.h>
     3 #include <cstdlib>
     4 #include <cstdio>
     5 #include <iostream>
     6 #include <cstdlib>
     7 #include <cstring>
     8 #include <algorithm>
     9 #include <cmath>
    10 #include <cctype>
    11 #include <map>
    12 #include <set>
    13 #include <queue>
    14 #include <bitset>
    15 #include <string>
    16 #include <complex>
    17 #define LL long long
    18 #define mod 1000000007
    19 using namespace std;
    20 LL x,d12,d23,d34,d41;
    21 int t;
    22 struct node{
    23     LL st,we,dis;
    24 }exm,ok;
    25 int vis[5][60004];
    26 int dp[5][60004];
    27 LL d[5][5];
    28 LL bew;
    29 queue<node> q;
    30 void dij()
    31 {
    32     while(!q.empty())
    33         q.pop();
    34     exm.st=2;
    35     exm.we=0;
    36     exm.dis=0;
    37     q.push(exm);
    38     dp[2][0]=0;
    39     vis[exm.st][exm.we]=1;
    40     while(!q.empty()){
    41         exm=q.front();
    42         q.pop();
    43         vis[exm.st][exm.we]=0;
    44         LL now,ww;
    45         now=(exm.st)%4+1;
    46         ww=(exm.dis+d[exm.st][now])%(2*bew);
    47         if(dp[now][ww]==-1||dp[now][ww]>=exm.dis+d[exm.st][now]){
    48             dp[now][ww]=exm.dis+d[exm.st][now];
    49             if(vis[now][ww]==0){
    50             vis[now][ww]=1;
    51             ok.st=now;
    52             ok.we=ww;
    53             ok.dis=exm.dis+d[exm.st][now];
    54             q.push(ok);
    55             }
    56         }
    57         now=(exm.st-1);
    58         if(now==0)
    59             now=4;
    60         ww=(exm.dis+d[exm.st][now])%(2*bew);
    61         if(dp[now][ww]==-1||dp[now][ww]>=exm.dis+d[exm.st][now]){
    62             dp[now][ww]=exm.dis+d[exm.st][now];
    63             if(vis[now][ww]==0){
    64             vis[now][ww]=1;
    65             ok.st=now;
    66             ok.we=ww;
    67             ok.dis=exm.dis+d[exm.st][now];
    68             q.push(ok);
    69         }
    70         }
    71     }
    72 
    73 }
    74 int main()
    75 {
    76     scanf("%d",&t);
    77     for(int i=1;i<=t;i++){
    78         memset(vis,0,sizeof(vis));
    79         memset(dp,-1,sizeof(dp));
    80         scanf("%lld %lld %lld %lld %lld",&x,&d[1][2],&d[2][3],&d[3][4],&d[4][1]);
    81         d[2][1]=d[1][2];
    82         d[3][2]=d[2][3];
    83         d[4][3]=d[3][4];
    84         d[1][4]=d[4][1];
    85         bew=min(d[2][1],d[2][3]);
    86         dij();
    87         LL ans=1e18+1;
    88         for(LL j=0;j<2*bew;j++){
    89             if(dp[2][j]==-1)
    90                 continue;
    91             LL zhong=(max(0LL,x-dp[2][j]))/(2*bew);
    92           if(dp[2][j]+zhong*2*bew<x)
    93             zhong++;
    94          ans=min(ans,dp[2][j]+zhong*2*bew);
    95        }
    96        printf("%lld
    ",ans);
    97     }
    98     return 0;
    99 }
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  • 原文地址:https://www.cnblogs.com/hsd-/p/7289784.html
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