Task Schedule(Hdu3572网络流)

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Task Schedule(Hdu3572网络流)

题意: 有一个工厂最近新近了一批机器人,这些机器人被用来解决若干个任务.每个任务都有完成所需的时间pi和规定了必须在si天或者si天之后才能处理这个任务,且需要在ei天之内完成. 工厂规定每个机器人每天只能处理一个任务,且每个任务最多只能由一个机器处理. 问这些机器人能否在顺利完成这些任务.

题解: 网络流建模. 对于每一个任务来说,它必须要在si到ei天之间被处理. 并且要在pi天以内完成. 所以我们可以把每一天当成点来考虑,那么每天就有m个机器在工作,相当于每一天有流量为m的物品流向任务区,每个任务也当成点,那么为了保证每个任务每天只能有一个机器人处理,那我们从就可以从天这些点往任务连边,然后每个任务往汇点t流一条流量为pi的边,同理,汇点s往天数连一条流量为m的边.这样就是跑最大流,看最后是不是满流就可以了.

/* ***********************************************
Author        :xdlove
Created Time  :2015年08月18日 星期二 21时48分52秒
File Name     :a.cpp
************************************************ */

#include <stdio.h>
#include <string.h>
#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <string>
#include <math.h>
#include <stdlib.h>
#include <time.h>
using namespace std;

const int MAXN = 1100;
const int MAXM = 2e6;
const int INF = 0x3f3f3f3f;

struct Node
{
    int from,to,next;
    int cap;
}edge[MAXM * 2];
int tol;
int Head[MAXN];
int que[MAXN];
int dep[MAXN]; //dep为点的层次
int stack[MAXN];//stack为栈，存储当前增广路
int cur[MAXN];//存储当前点的后继

void Init()
{
    tol = 0;
    memset(Head,-1,sizeof(Head));
}

void add_edge(int u, int v, int w)
{
    edge[tol].from = u;
    edge[tol].to = v;
    edge[tol].cap = w;
    edge[tol].next = Head[u];
    Head[u] = tol++;
    edge[tol].from = v;
    edge[tol].to = u;
    edge[tol].cap = 0;
    edge[tol].next = Head[v];
    Head[v] = tol++;
}

int BFS(int start, int end)
{
    int front, rear;
    front = rear = 0;
    memset(dep, -1, sizeof(dep));
    que[rear++] = start;
    dep[start] = 0;
    while (front != rear)
    {
        int u = que[front++];
        if (front == MAXN)front = 0;
        for (int i = Head[u]; i != -1; i = edge[i].next)
        {
            int v = edge[i].to;
            if (edge[i].cap > 0 && dep[v] == -1)
            {
                dep[v] = dep[u] + 1;
                que[rear++] = v;
                if (rear >= MAXN)rear = 0;
                if (v == end)return 1;
            }
        }
    }
    return 0;
}

int dinic(int start, int end)
{
    int res = 0;
    int top;
    while (BFS(start, end))
    {
        memcpy(cur, Head, sizeof(Head));
        int u = start;
        top = 0;
        while (true)
        {
            if (u == end)
            {
                int min = INF;
                int loc;
                for (int i = 0; i < top; i++)
                    if (min > edge[stack[i]].cap)
                    {
                        min = edge[stack[i]].cap;
                        loc = i;
                    }
                for (int i = 0; i < top; i++)
                {
                    edge[stack[i]].cap -= min;
                    edge[stack[i] ^ 1].cap += min;
                }
                res += min;
                top = loc;
                u = edge[stack[top]].from;
            }
            for (int i = cur[u]; i != -1; cur[u] = i = edge[i].next)
                if (edge[i].cap != 0 && dep[u] + 1 == dep[edge[i].to])
                    break;
            if (cur[u] != -1)
            {
                stack[top++] = cur[u];
                u = edge[cur[u]].to;
            }
            else
            {
                if (top == 0)break;
                dep[u] = -1;
                u = edge[stack[--top]].from;
            }
        }
    }
    return res;
}


int main()
{
    //freopen("in.txt","r",stdin);
    //freopen("out.txt","w",stdout);
    int T,n,m;
    int cnt = 0;
    cin>>T;
    while(T--)
    {
        scanf("%d %d",&n,&m);
        Init();
        int s = 0;
        int t = 1001;
        int sum = 0;
        for(int i = 1; i <= n; i++)
        {
            int p,s,e;
            scanf("%d %d %d",&p,&s,&e);
            for(int k = s; k <= e; k++)
                add_edge(k,500 + i,1);
            add_edge(500 + i,t,p);
            sum += p;
        }
        for(int i = 1; i <= 500; i++)
            add_edge(s,i,m);
        int ans = dinic(s,t);
        printf("Case %d: ",++cnt);
        puts(ans == sum ? "Yes" : "No");
        puts("");
    }
    return 0;
}