zoukankan      html  css  js  c++  java
  • POJ

    Truck History

    题目链接:

    http://poj.org/problem?id=1789

    题目:

    Time Limit: 2000MS   Memory Limit: 65536K
    Total Submissions: 33974   Accepted: 13146

    Description

    Advanced Cargo Movement, Ltd. uses trucks of different types. Some trucks are used for vegetable delivery, other for furniture, or for bricks. The company has its own code describing each type of a truck. The code is simply a string of exactly seven lowercase letters (each letter on each position has a very special meaning but that is unimportant for this task). At the beginning of company's history, just a single truck type was used but later other types were derived from it, then from the new types another types were derived, and so on. 

    Today, ACM is rich enough to pay historians to study its history. One thing historians tried to find out is so called derivation plan -- i.e. how the truck types were derived. They defined the distance of truck types as the number of positions with different letters in truck type codes. They also assumed that each truck type was derived from exactly one other truck type (except for the first truck type which was not derived from any other type). The quality of a derivation plan was then defined as 

    1/Σ(to,td)d(to,td)


    where the sum goes over all pairs of types in the derivation plan such that to is the original type and td the type derived from it and d(to,td) is the distance of the types. 
    Since historians failed, you are to write a program to help them. Given the codes of truck types, your program should find the highest possible quality of a derivation plan. 

    Input

    The input consists of several test cases. Each test case begins with a line containing the number of truck types, N, 2 <= N <= 2 000. Each of the following N lines of input contains one truck type code (a string of seven lowercase letters). You may assume that the codes uniquely describe the trucks, i.e., no two of these N lines are the same. The input is terminated with zero at the place of number of truck types.

    Output

    For each test case, your program should output the text "The highest possible quality is 1/Q.", where 1/Q is the quality of the best derivation plan.

    Sample Input

    4
    aaaaaaa
    baaaaaa
    abaaaaa
    aabaaaa
    0

    Sample Output

    The highest possible quality is 1/3.

    题目大意:

    给出n个长度为7的字符串,每个字符串代表一个车,定义车的距离是两个字符串间不同字母的个数,题目要求连接所有车的最短距离

    Prime算法:

    #include <stdio.h>
    #include <string.h>
    #include <iostream>
    using namespace std;
     
    const int inf = 0x3f3f3f3f;
    char str[2005][10];
    int road[2005][2005],minroad,dis[2005],vis[2005],n;
     
    int dist(int x,int y)
    {
        int d=0;
        for(int i=0;i<7;i++)
            if(str[x][i]!=str[y][i])
                d++;
        return d;
    }
     
    int prime()
    {
        memset(vis,0,sizeof(vis));
        for(int i=1;i<=n;i++)
            dis[i]=road[1][i];
        vis[1]=1;
        int sum=0;
        int c=1;
        int i,j;
        while( c < n )
        {
            minroad = inf;
            for(j=0,i=1;i<=n;i++)
            {
                if(vis[i]==0 && minroad>dis[i])
                {
                    minroad = dis[i];
                    j=i;
                }
            }
            sum += minroad;
            c++;
            vis[j]=1;
            for(i=1;i<=n;i++)
                if(vis[i]==0 && road[j][i]<dis[i])
                dis[i] = road[j][i];
        }
        return sum;
    }
     
    int main()
    {
        while(scanf("%d",&n)!=EOF)
        {
            getchar();
            if(n==0) break;
            for(int i=1;i<=n;i++)
                scanf("%s",str[i]);
            for(int i=1;i<=n;i++)
                for(int j=1;j<=n;j++)
                    if(i==j) road[i][j]=0;
                    else road[i][j]=inf;
            for(int i=1;i<=n;i++)
                for(int j=1;j<=n;j++)
                    road[i][j] = dist(i,j);
            printf("The highest possible quality is 1/%d.
    ",prime());
        }
        return 0;
    }

    krustal算法:

    #include <stdio.h>
    #include <string.h>
    #include <iostream>
    #include <algorithm>
    using namespace std;
     
    const int maxn = 2010;
    char str[maxn][10];
    int n,allroad,vis[maxn];
     
    struct r
    {
        int a,b,dis;
    }road[maxn*maxn];
     
    int dist(int x,int y)
    {
        int d=0;
        for(int i=0;i<7;i++)
            if(str[x][i]!=str[y][i])
                d++;
        return d;
    }
     
    bool cmp(r a,r b)
    {
        return a.dis<b.dis;
    }
     
    int findd(int x)
    {
        int a=x;
        while(vis[x]!=x) x=vis[x];
        while(x!=vis[x])
        {
            int z=a;
            a=vis[a];
            vis[z]=x;
        }
        return x;
    }
     
    int krustal()
    {
        sort(road,road+allroad,cmp);
        for(int i=1;i<=n;i++) vis[i]=i;
        int c=0,sum=0;
        for(int i=0;i<allroad;i++)
        {
            int ha=findd(road[i].a);
            int hb=findd(road[i].b);
            if(ha!=hb)
            {
                c++;
                vis[ha]=hb;
                sum += road[i].dis;
                if(c == n-1)break;
            }
        }
        return sum;
    }
     
    int main()
    {
        while(scanf("%d",&n)!=EOF)
        {
            getchar();
            if(n==0) break;
            for(int i=1;i<=n;i++)
                scanf("%s",str[i]);
            allroad = 0;
            for(int i=1;i<=n;i++)
                for(int j=i+1;j<=n;j++)
                    {
                        road[allroad].a=i;
                        road[allroad].b=j;
                        road[allroad].dis = dist(i,j);
                        allroad++;
                    }
            printf("The highest possible quality is 1/%d.
    ",krustal());
        }
        return 0;
    }
  • 相关阅读:
    【转】[完结] 取结构偏移 和 取地址符号的 思考
    资料备忘 【攀枝花】 我的百度文库
    static_cast reinterprt_cast 区别
    c++ 四种转换 cast 列表小结 (等待补充)2012 3月
    对偏移表达式的 思考过程—how offset macro is think out
    【转】常见面试题思想方法整理 原来果然有双指针遍历
    [转]好的习惯 提高你开发效率的十五个Visual Studio 2010使用技巧
    多种方案 测试 有无符号数包括 不适用大小于符号判断符号数
    [转] 仅有USB线拷贝无SD卡小米照相文件方法 简言adb shell
    iframe 高度自动调节
  • 原文地址:https://www.cnblogs.com/20172674xi/p/9671370.html
Copyright © 2011-2022 走看看