Problem K: Yikes -- Bikes!

 

http://acm.upc.edu.cn/problem.php?id=2780

昨天做的题，没过……！！！伤心……
题意：给你n个单位，n-1组关系，让你单位换算……
解题思路：Floyd算法
自己听别人说用Floyd算法，然后自己默默的用有向图写……但是！！！Floyd算法不能用有向图……！所以只能在其相反的转化中标记为负的，在进行时特殊处理一下，最后便利找出能进行单位转化的那组单位，然后进行大小排序，最后就莫名其妙的哦过了……！！！

#include <iostream>

#include <cstdio>

#include <cstdlib>

#include <algorithm>

#include <map>

#include <cmath>

#include <cstring>

#include <string>

#include <queue>

#include <stack>

#include <cctype>

#include <set>

#define ALL(x) x.begin(),x.end()

#define INS(x) inserter(x,x.begin())



typedef long long LL;



using namespace std;



int graph[30][30];

int c[30];

int topo[30];

int n;

int t;

struct Value{

    int x,y;

};



bool cmp(Value a,Value b){

    return a.x > b.x;

}



int main()

{

#ifndef ONLINE_JUDGE

   freopen("in.in","r",stdin);

#endif

    map<string,int>un;

    string name[30];

    while(cin >> n && n){

    for(int i = 1;i <= n;i++){

        cin >> name[i];

        un[ name[i] ] = i;

    }

    memset(graph,0,sizeof(graph));

    for(int i = 1;i <= n-1;i++){

        string str1;

        int num,a,b;

        cin >> str1;

        a = un[str1];

        cin >> str1 >> num >> str1;

        b = un[str1];

        graph[a][b] = num;

        graph[b][a] = -1 *num;

        //cout <<a << " " << b << endl;

    }

    for(int k = 1;k <= n;k++){

        for(int i = 1;i <= n;i++){

            for(int j = 1;j <= n;j++){

                if(i == j || k == i || k == j)

                    continue;

                if(!graph[i][j] &&graph[i][k] &&graph[k][j]){

                    if(graph[i][k] > 0 && graph[k][j] > 0){

                        graph[i][j] = graph[i][k] * graph[k][j];

                        graph[j][i] = -1 * graph[i][k] * graph[k][j];

                    }

                    else if(graph[i][k] < 0 && graph[k][j] < 0){

                        graph[j][i] = graph[i][k] * graph[k][j];

                        graph[i][j] = -1 * graph[i][k] * graph[k][j];

                    }

                    else if(graph[i][k] < 0 && graph[k][j] > 0){

                        if(abs(graph[i][k]) > graph[k][j]){

                            graph[j][i] = abs(graph[i][k]) / graph[k][j];

                            graph[i][j] = -1 * graph[j][i];

                        }

                        else{

                            graph[i][j] = abs(graph[i][k]) / graph[k][j];

                            graph[j][i] = -1 * graph[i][j];

                        }

                    }

                    else{

                        if(graph[i][k] > abs(graph[k][j])){

                            graph[i][j] = graph[i][k] / abs(graph[k][j]);

                            graph[j][i] = -1 * graph[i][j];

                        }

                        else{

                            graph[j][i] = graph[i][k] / abs(graph[k][j]);

                            graph[i][j] = -1 * graph[j][i];

                        }

                    }

                }

            }

        }

    }

    int mark;

    for(int i = 1;i <= n;i++){

        bool flag = 1;;

        for(int j = 1;j <= n;j++){

            if(graph[i][j] < 0){

                flag = 0;

                break;

            }

        }

        if(flag){

            mark = i;

            break;

        }

    }

    Value a[30];

    for(int i = 1;i <= n;i++){

        a[i-1].x = graph[mark][i];

        a[i-1].y = i;

    }

    sort(a,a+n,cmp);

    cout << 1  << name[ a[n-1].y ];

    for(int i = n-2;i > -1;i--){

        cout << " = "<< a[i].x << name[ a[i].y ] ;

    }

    cout << endl;

    }

    return 0;

}

View Code