贝尔曼福特 题目(Wormholes,Currency Exchange)

Wormholes

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.*;

public class source {
    public static void main(String[] args) throws Exception {
        BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st = new StringTokenizer(bf.readLine());
        int T = Integer.parseInt(st.nextToken());
        for(int testCase = 1;testCase<=T;testCase++){
            st = new StringTokenizer(bf.readLine());
            int N = Integer.parseInt(st.nextToken());
            int M = Integer.parseInt(st.nextToken());
            int W = Integer.parseInt(st.nextToken());
            List<Edge> conn = new ArrayList<Edge>();
            for(int i = 1;i<=M;i++){
                st = new StringTokenizer(bf.readLine());
                int start = Integer.parseInt(st.nextToken());
                int end = Integer.parseInt(st.nextToken());
                int time = Integer.parseInt(st.nextToken());
                Edge edge1 = new Edge(start,end,time);
                Edge edge2 = new Edge(end,start,time);
                conn.add(edge1);
                conn.add(edge2);
            }

            for(int i = 1;i<=W;i++){
                st = new StringTokenizer(bf.readLine());
                int start = Integer.parseInt(st.nextToken());
                int end = Integer.parseInt(st.nextToken());
                int time = Integer.parseInt(st.nextToken());
                Edge edge = new Edge(start,end,-time);
                conn.add(edge);
            }

            long[] time = new long[N+1];
            Arrays.fill(time,100000000);
            time[1] = 0;
            long transTime;
            for(int i = 0;i<N;i++){
                for(Edge edge:conn){
                    transTime = time[edge.start]+edge.time;
                    if(time[edge.end]>transTime){
                        time[edge.end] = transTime;
                    }
                }
            }

            boolean canBack = false;
            for(Edge edge:conn){
                transTime = time[edge.start]+edge.time;
                if(time[edge.end]>transTime){
                    canBack = true;
                    break;
                }
            }
            if(canBack){
                System.out.println("YES");
            }
            else{
                System.out.println("NO");
            }
        }
    }



    static class Edge{
        int start;
        int end;
        int time;
        Edge(int start,int end,int time){
            this.start = start;
            this.end = end;
            this.time = time;
        }
    }
}

1860:Currency Exchange

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Main {
    public static void main(String[] args) throws Exception {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st = new StringTokenizer(br.readLine());
        int N = Integer.parseInt(st.nextToken());
        int M = Integer.parseInt(st.nextToken());
        int S = Integer.parseInt(st.nextToken());
        double V = Double.parseDouble(st.nextToken());

        int start;
        int end;
        double rSE;
        double cSE;
        double rES;
        double cES;

        Object[][] road = new Object[2*M][4];
        for(int i = 0;i<2*M;i+=2){
            st = new StringTokenizer(br.readLine());
            start = Integer.parseInt(st.nextToken());
            end = Integer.parseInt(st.nextToken());
            rSE = Double.parseDouble(st.nextToken());
            cSE = Double.parseDouble(st.nextToken());
            rES = Double.parseDouble(st.nextToken());
            cES = Double.parseDouble(st.nextToken());
            road[i] = new Object[]{start,end,rSE,cSE};
            road[i+1] = new Object[]{end,start,rES,cES};
        }

        double[] visited = new double[N+1];
        visited[S] = V;
        Object[] current;
        double exchangeValue;
        for(int i = 0;i<N;i++){
            for(int j = 0;j<2*M;j++){
                current = road[j];
                exchangeValue = (visited[(int)current[0]]-(double)current[3])*(double)current[2];
                if(visited[(int)current[1]]<exchangeValue){
                    visited[(int)current[1]] = exchangeValue;
                }
            }
        }
        boolean flag = false;
        for(int j = 0;j<2*M;j++){
            current = road[j];
            exchangeValue = (visited[(int)current[0]]-(double)current[3])*(double)current[2];
            if(visited[(int)current[1]]<exchangeValue){
                flag = true;
                visited[(int)current[1]] = exchangeValue;
            }
        }
        if(flag){
            System.out.println("YES");
        }
        else{
            System.out.println("NO");
        }
    }
}