在预算内拆解任务与协作

CompletableFuture<Void> joined = CompletableFuture.allOf(first, second);
joined.thenRun(() -> mergeValidatedResults(first.join(), second.join()));
// allOf协调已经创建的任务完成，不自动限制并发或合并业务证据。
// 一个子任务失败会影响组合完成状态；取消和资源清理仍需显式设计。

import java.util.*;
public class Main {
    record Plan(long finish,List<Integer> path){}
    static Plan critical(long[] duration,int[][] edges){
        int n=duration.length;for(long d:duration)if(d<0)throw new IllegalArgumentException("duration");
        List<List<Integer>> g=new ArrayList<>();for(int i=0;i<n;i++)g.add(new ArrayList<>());
        int[] indegree=new int[n],previous=new int[n];Arrays.fill(previous,-1);long[] start=new long[n],finish=new long[n];
        for(int[] e:edges){if(e.length!=2||e[0]<0||e[1]<0||e[0]>=n||e[1]>=n)throw new IllegalArgumentException("edge");g.get(e[0]).add(e[1]);indegree[e[1]]++;}
        Deque<Integer> q=new ArrayDeque<>();for(int i=0;i<n;i++)if(indegree[i]==0)q.add(i);int processed=0;
        while(!q.isEmpty()){
            int u=q.removeFirst();processed++;finish[u]=Math.addExact(start[u],duration[u]); // 时间溢出明确失败。
            for(int v:g.get(u)){
                if(finish[u]>start[v]||finish[u]==start[v]&&(previous[v]<0||u<previous[v])){start[v]=finish[u];previous[v]=u;} // 保存最大前驱。
                if(--indegree[v]==0)q.addLast(v); // 全部依赖处理后才允许开始。
            }
        }
        if(processed!=n)throw new IllegalArgumentException("cycle");if(n==0)return new Plan(0,List.of());
        int end=0;for(int i=1;i<n;i++)if(finish[i]>finish[end])end=i;
        List<Integer> path=new ArrayList<>();for(int p=end;p>=0;p=previous[p])path.add(p);Collections.reverse(path);return new Plan(finish[end],path);
    }
    static void eq(Plan e,Plan a){if(!e.equals(a))throw new AssertionError(a);}
    public static void main(String[] args){
        eq(new Plan(7,List.of(1,2)),critical(new long[]{3,5,2},new int[][]{{0,2},{1,2}}));
        eq(new Plan(5,List.of(1)),critical(new long[]{3,5},new int[][]{}));
        eq(new Plan(0,List.of()),critical(new long[]{},new int[][]{}));
        eq(new Plan(3,List.of(0,1)),critical(new long[]{0,3},new int[][]{{0,1}}));
        try{critical(new long[]{1,1},new int[][]{{0,1},{1,0}});throw new AssertionError();}catch(IllegalArgumentException expected){}
        System.out.println("PASS 5 tests");
    }
}