USACO 3.2 Sweet Butter

这个题时间是个大问题，用heap优化的迪杰斯特拉过的。

TASK: butter
LANG: C++

Compiling...
Compile: OK

Executing...
   Test 1: TEST OK [0.000 secs, 12192 KB]
   Test 2: TEST OK [0.000 secs, 12192 KB]
   Test 3: TEST OK [0.000 secs, 12192 KB]
   Test 4: TEST OK [0.000 secs, 12192 KB]
   Test 5: TEST OK [0.000 secs, 12192 KB]
   Test 6: TEST OK [0.000 secs, 12192 KB]
   Test 7: TEST OK [0.027 secs, 12192 KB]
   Test 8: TEST OK [0.108 secs, 12192 KB]
   Test 9: TEST OK [0.135 secs, 12192 KB]
   Test 10: TEST OK [0.135 secs, 12192 KB]

All tests OK.

  1 /*
  2 PROG: butter
  3 ID: jiafeim1
  4 LANG: C++
  5  */
  6 
  7 #include <stdio.h>
  8 #include <string.h>
  9 #define MAXINT 100000000
 10 int cow_count;
 11 int heap_size;
 12 int value_heap[805];
 13 int id_heap[805];
 14 int heap_clue[805];
 15 int cows[805];
 16 
 17 int road_to[805][1455];
 18 int road_cost[805][1455];
 19 int road_count[805]={0};
 20 
 21 int res[805]={0};
 22 
 23 bool haveGo[805];
 24 
 25 void heap_swap(int i ,int j)
 26 {
 27     int temp;
 28     temp = value_heap[i];
 29     value_heap[i]=value_heap[j];
 30     value_heap[j] = temp; 
 31     
 32     heap_clue[id_heap[i]]=j;
 33     heap_clue[id_heap[j]]=i;
 34     
 35     temp = id_heap[i];
 36     id_heap[i]=id_heap[j];
 37     id_heap[j] = temp;
 38 }
 39 
 40 void heap_up(int i)
 41 {
 42     while(i>0 && value_heap[i]<value_heap[(i-1)/2])
 43     {
 44         heap_swap(i,(i-1)/2);
 45         i=(i-1)/2;
 46     }
 47 }
 48 void heap_down(int j)
 49 {
 50     bool haveDo;
 51     do
 52     {
 53         haveDo = false;
 54         int left = 2*j+1;
 55         int right = 2*j+2;
 56         if(right<heap_size && value_heap[right]<value_heap[j] && value_heap[right]<value_heap[left])
 57         {
 58             heap_swap(j,right);
 59             j = right;
 60             haveDo = true;
 61             continue;
 62         }
 63         if(left<heap_size && value_heap[left]<value_heap[j])
 64         {
 65             heap_swap(j,left);
 66             j = left;
 67             haveDo = true;
 68             continue;
 69         }   
 70     }while(haveDo);
 71 }
 72 int main()
 73 {
 74     FILE *fin = fopen("butter.in", "r");
 75     FILE *fout = fopen("butter.out", "w");
 76 
 77     int n,p,c;
 78     fscanf(fin,"%d%d%d",&n,&p,&c);
 79     for(int i = 0;i<n;++i)
 80     {
 81         fscanf(fin,"%d",&(cows[i]));
 82         --cows[i];
 83     }
 84 
 85     int t1,t2,tc;
 86     for(int i=0;i<c;++i)
 87     {
 88         fscanf(fin,"%d%d%d",&t1,&t2,&tc);
 89         --t1;
 90         --t2;
 91         road_cost[t1][road_count[t1]]=tc;
 92         road_to[t1][road_count[t1]]=t2;
 93         ++road_count[t1];
 94 
 95         road_cost[t2][road_count[t2]]=tc;
 96         road_to[t2][road_count[t2]]=t1;
 97         ++road_count[t2];
 98     }
 99     for(int co = 0;co<n;++co)
100     {
101         int nowCo = cows[co],curid;
102         heap_size = p;
103         for(int ba=0;ba<p;++ba)
104         {
105             value_heap[ba] = MAXINT;
106             id_heap[ba] = ba;
107             heap_clue[ba] = ba;
108         }
109         memset(haveGo,false,p*sizeof(bool));
110         value_heap[nowCo] = 0;
111         heap_up(nowCo);
112         for(int ba=0;ba<p;++ba)
113         {
114             curid = id_heap[0];
115             haveGo[curid] = true;       
116             heap_swap(0,heap_size-1);
117             --heap_size;
118             heap_down(0);
119             for(int side = 0;side<road_count[curid];++side)
120             {
121                 int curSideTo = road_to[curid][side];
122                 if(!haveGo[curSideTo] && value_heap[heap_clue[curSideTo]]>value_heap[heap_clue[curid]]+road_cost[curid][side])
123                 {
124                     value_heap[heap_clue[curSideTo]] = value_heap[heap_clue[curid]]+road_cost[curid][side];
125                     heap_up(heap_clue[curSideTo]);
126                 }
127             }
128         }
129         for(int i = 0;i<p;++i)
130         {
131             res[i]+=value_heap[heap_clue[i]];
132         }
133     }
134 
135     int tempMin = MAXINT;
136     for(int i = 0;i<p;++i)
137     {
138         if(res[i]<tempMin)
139         {
140             tempMin = res[i];
141         }
142     }
143     fprintf(fout,"%d\n",tempMin);
144     fclose(fin);
145     fclose(fout);
146     return 0;
147 }
posted @ 2011-05-27 21:36  幻魇  阅读(272)  评论(0)    收藏  举报