題目鏈接：https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&category=9&problem=698&mosmsg=Submission+received+with+ID+19496827

利用枚舉和貪心來計算。枚舉在每個湖stop fishing的情況，在每種情況下，貪心算法得出能釣得最多魚的數目。因為題目要求：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.

  1 //============================================================================
  2 // Name        : test.cpp
  3 // Author      : 
  4 // Version     :
  5 // Copyright   : Your copyright notice
 
  6 // Description : Hello World in C++, Ansi-style
  7 //============================================================================
  8 
  9 #include <iostream>
 10 #include <math.h>
 11 #include <stdio.h>
 12 #include <cstdio>
 13 #include <algorithm>
 14 #include <string
 
.h>
 15 #include <cstring>
 16 #include <queue>
 17 #include <vector>
 18 #include <functional>
 19 #include <cmath>
 20 #define SCF(a) scanf("%d", &a)
 21 #define IN(a) cin>>a
 22 #define FOR(i, a, b) for(int i=a;i<b;i++)
 23 typedef long long Int;
 24 using namespace std;
 25 
 26 int main()
 27 {
 28     int n, h; //n lakes, h hours = h*12 "5 minutes"
 29     int fish[30]; //initial fish number
 30     int decrease[30]; //decrese unit
 31     int time[30]; //walk time
 32     int tcase = 0;
 33     int stay[30]; //time that stay at lake i
 34     int take[30]; //time to take for people walk from lake 0 to lake i;
 35     while (SCF(n) && n)
 36     {
 37         if (tcase >= 1)
 38             printf("\n");
 39         SCF(h);
 40         FOR(i, 0, n)
 41             SCF(fish[i]);
 42         FOR(i, 0, n)
 43             SCF(decrease[i]);
 44         FOR(i, 0, n - 1)
 45             SCF(time[i]);
 46         FOR(i, 0, n)
 47             stay[i] = 0;
 48 
 49         take[0] = 0;
 50         FOR(i, 1, n)
 51             take[i] = take[i - 1] + time[i-1];
 52         
 53         int maxFish = 0;
 54         int left[30]; //record available fish for each lake
 55         int cfish = 0; //total fish that can get for current strategy
 56         int cstay[30]; //record the time stay at each lake
 57         int ctime = h * 12;
 58         
 59         FOR(i, 0, n) //fishing destination is lake i
 60         {
 61             ctime = h * 12;
 62             cfish = 0;
 63 
 64             ctime -= take[i];
 65             FOR(j, 0, n)
 66             {
 67                 left[j] = fish[j];
 68                 cstay[j] = 0;
 69             }
 70             
 71             while (ctime > 0)
 72             {
 73                 int cmax = 0;
 74                 FOR(j, 0, i+1)
 75                 {
 76                     if (left[j] > left[cmax])
 77                         cmax = j;
 78                 }
 79                 cfish += left[cmax];
 80                 left[cmax] = max(0, left[cmax] - decrease[cmax]);
 81                 cstay[cmax] += 5;
 82                 ctime -= 1;
 83             }
 84 
 85             if (cfish > maxFish)
 86             {
 87                 maxFish = cfish;
 88                 FOR(j, 0, n)
 89                     stay[j] = cstay[j];
 90             }
 91             else if (cfish == maxFish)
 92             {
 93                 FOR(j, 0, n)
 94                 {
 95                     if (cstay[j] > stay[j])
 96                     {
 97                         FOR(z, j, n)
 98                             stay[z] = cstay[z];
 99                         break;
100                     }
101                     else if (cstay[j] < stay[j])
102                         break;
103                 }
104             }
105         }
106 
107         printf("%d", stay[0]);
108         FOR(i, 1, n)
109             printf(", %d", stay[i]);
110         printf("\n");
111         printf("Number of fish expected: %d\n", maxFish);
112         tcase++;
113     }
114     return 0;
115 }

剛開始沒有寫91行else if的情況，以為在貪心算法中就已經考慮優先選擇靠前的湖就可以了，結果一直wrong answer。加上之後才AC。

UVA 757 Gone Fishing