贪心算法
注意两点：
1、sum用double类型
2、第二个测试点是起点没有加油站的情况
AC代码
1 #include <vector>
2 #include <cstdio>
3 #include <algorithm>
4 #include <map>
5 using namespace std;
6 class gas{
7 public:
8 double p;
9 double d;
10 };
11 bool operator<(const gas& a,const gas& b){
12 return a.d < b.d;
13 }
14 int main(){
15 int c,d,avg,n;
16 scanf("%d %d %d %d",&c,&d,&avg,&n);
17 double D(c * avg);
18 vector<gas> g;
19 map<double,gas> minG;
20 for(int i = 0;i < n;i++){
21 gas tmp;
22 scanf("%lf %lf",&tmp.p,&tmp.d);
23 if(minG.find(tmp.d) == minG.end() || minG[tmp.d].p > tmp.p)
24 minG[tmp.d] = tmp;
25 }
26 for(map<double,gas>::iterator ite = minG.begin();ite != minG.end();ite++){
27 g.push_back(ite->second);
28 }
29 //sort(g.begin(),g.end());
30 int currentId(0);
31 float rem(0);
32 double sum(0);
33 if(g[0].d > 0){
34 printf("The maximum travel distance = 0.00\n");
35 return 0;
36 }
37 for(int i = 0;i < g.size();i++){
38 if(i != g.size() - 1){
39 if(g[i + 1].d < d && g[i + 1].d - g[i].d > D || g[i + 1].d > d && d - g[i].d > D){
40 printf("The maximum travel distance = %.2lf\n",g[i].d + D);
41 return 0;
42 }
43 if(g[i].d + D >= d){
44 int j;
45 for(j = i + 1;j < g.size() && g[j].d < d;j++){
46 if(g[j].p < g[i].p)
47 break;
48 }
49 if(j == g.size() || g[j].p >= g[i].p){
50 if(rem >= d - g[i].d)
51 printf("%.2lf\n",sum);
52 else
53 printf("%.2lf\n",sum + (d - g[i].d - rem) / avg * g[i].p);
54 return 0;
55 }
56 }
57 int j;
58 bool s1(false);
59 double minP;
60 int minId;
61 for(j = i + 1;j < g.size() && g[j].d <= g[i].d + D;j++){
62 if(j == i + 1 || g[j].p < minP){
63 minP = g[j].p;
64 minId = j;
65 }
66 if(g[j].p < g[i].p){
67 if(rem < g[j].d - g[i].d){
68 sum += (g[j].d - g[i].d - rem) / avg * g[i].p ;
69 rem = 0;
70 i = j - 1;
71 s1 = true;
72 break;
73 }
74 }
75 }
76 if(s1) continue;
77 if(j != g.size()){
78 sum += (D - rem) / avg * g[i].p;
79 rem = D - (g[minId].d - g[i].d);
80 i = minId - 1;
81 }
82 else{
83 if(g[j - 1].p < g[i].p){
84 if(g[j - 1].d - g[i].d > rem){
85 sum += (g[j - 1].d - g[i].d - rem) / avg * g[i].p;
86 rem = 0;
87 i = j - 2;
88 }
89 else{
90 rem -= g[j - 1].d - g[i].d;
91 i = j - 2;
92 }
93 }
94 else{
95 sum += (D - rem) / avg * g[i].p;
96 rem = D - (g[j - 1].d - g[i].d);
97 i = j - 2;
98 }
99 }
100 continue;
101 }
102 else{
103 if(g[i].d < d - D){
104 printf("The maximum travel distance = %.2lf\n",g[i].d + D);
105 return 0;
106 }
107 else{
108 if(rem >= d - g[i].d)
109 printf("%.2lf\n",sum);
110 else
111 printf("%.2lf\n",sum + (d - g[i].d - rem) / avg * g[i].p );
112 return 0;
113 }
114 }
115 }
116 }
时间： 2024-12-20 19:04:51