POJ 1042 Gone Fishing (贪心)
Gone Fishing
Description
John is going on a fishing trip. He has h hours available (1 <= h <= 16), and there are n lakes in the area (2 <= n <= 25) all reachable along a single, one-way road. John starts at lake 1, but he can finish at any lake he wants. He can only travel from one lake to the next one, but he does not have to stop at any lake unless he wishes to. For each i = 1,...,n - 1, the number of 5-minute intervals it takes to travel from lake i to lake i + 1 is denoted ti (0 < ti <=192). For example, t3 = 4 means that it takes 20 minutes to travel from lake 3 to lake 4. To help plan his fishing trip, John has gathered some information about the lakes. For each lake i, the number of fish expected to be caught in the initial 5 minutes, denoted fi( fi >= 0 ), is known. Each 5 minutes of fishing decreases the number of fish expected to be caught in the next 5-minute interval by a constant rate of di (di >= 0). If the number of fish expected to be caught in an interval is less than or equal to di , there will be no more fish left in the lake in the next interval. To simplify the planning, John assumes that no one else will be fishing at the lakes to affect the number of fish he expects to catch.
Write a program to help John plan his fishing trip to maximize the number of fish expected to be caught. The number of minutes spent at each lake must be a multiple of 5.
Input
You will be given a number of cases in the input. Each case starts with a line containing n. This is followed by a line containing h. Next, there is a line of n integers specifying fi (1 <= i <=n), then a line of n integers di (1 <=i <=n), and finally, a line of n - 1 integers ti (1 <=i <=n - 1). Input is terminated by a case in which n = 0.
Output
For each test case, print the number of minutes spent at each lake, separated by commas, for the plan achieving the maximum number of fish expected to be caught (you should print the entire plan on one line even if it exceeds 80 characters). This is followed by a line containing the number of fish expected.
If multiple plans exist, choose the one that spends as long as possible at lake 1, even if no fish are expected to be caught in some intervals. If there is still a tie, choose the one that spends as long as possible at lake 2, and so on. Insert a blank line between cases.
Sample Input
2
1
10 1
2 5
2
4
4
10 15 20 17
0 3 4 3
1 2 3
4
4
10 15 50 30
0 3 4 3
1 2 3
0 Sample Output
45, 5
Number of fish expected: 31
240, 0, 0, 0
Number of fish expected: 480
115, 10, 50, 35
Number of fish expected: 724 题意：John有h个小时的钓鱼时间，一共有n个湖泊，它们在一条直线上。从第1个湖开始，可以在任意一个湖停下，每到达一个湖，这个湖开始有f[i]条鱼，钓一次鱼需要5分钟，5分钟后(即钓完鱼后)这个湖的鱼的数量为上次数量减去d[i]，并且从第i个湖到第i+1个湖需要ti*5的时间。如果某个时间段期望钓到的鱼数小于或者等于di，那么下一个时间段湖中将不再有鱼剩下。为了简化计划，John假设没有其他钓鱼人影响到他的钓鱼数目。目标是让他能钓到的鱼最多。在每个湖他所花的时间必须是5分钟的倍数。
方法:重载<，利用优先队列来给最优钓鱼湖排序，具体思路还请看代码...
关于优先队列中每次队首元素可能不是一个湖，本蒟蒻思路良久，得出以下结论：
有人认为：
因为优先队列每次的队首元素可能不是一个湖。
觉得应该把中间步行回去的时间算进来。
实际上，是不用的，假设一种情况下每次的队首元素分别是0湖，1湖，0湖。
在实际钓鱼中就是在0湖钓鱼2次，在1湖钓鱼1次。
相当于优先队列使这个人提前知道应该在哪个湖钓几次，而不是每次来回去找可以钓鱼最多的那个湖
Code :
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