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 "); 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 ",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 ",sum); 52 else 53 printf("%.2lf ",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 ",g[i].d + D); 105 return 0; 106 } 107 else{ 108 if(rem >= d - g[i].d) 109 printf("%.2lf ",sum); 110 else 111 printf("%.2lf ",sum + (d - g[i].d - rem) / avg * g[i].p ); 112 return 0; 113 } 114 } 115 } 116 }