12/9宿題

20151209/src/enshu_20151209/data/romania2.dat

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+# Romanian Cities and Road Network Graph
+# (See Russell & Norvig  Chapter 3 )
+#
+Oradea 380 Zerind 71 Sibiu 151
+Arad 366 Zerind 75 Sibiu 140 Timisoara 118
+Zerind 374 Arad 75 Oradea 71
+Timisoara 329 Arad 118 Lugoj 111
+Sibiu 253 Oradea 151 Arad 140 Fagaras 99 Rimnicu-Vilcea 80
+Lugoj 244 Timisoara 111 Mehadia 70
+Mehadia 241 Lugoj 70 Dobreta 75
+Dobreta 242 Mehadia 75 Craiova 120
+Craiova 160 Rimnicu-Vilcea 146 Pitesti 138 Dobreta 120
+Pitesti 100 Rimnicu-Vilcea 97 Craiova 138 Bucharest 101
+Rimnicu-Vilcea 193 Sibiu 80 Craiova 146 Pitesti 97
+Fagaras 176 Sibiu 99 Bucharest 211
+Bucharest 0 Fagaras 211 Giurgiu 90 Urziceni 85 Pitesti 101
+Giurgiu 77 Bucharest 90
+Urziceni 80 Bucharest 85 Hirsova 98 Vaslui 142
+Vaslui 199 Iasi 92 Urziceni 142
+Iasi 227 Neamt 87 Vaslui 92
+Neamt 234 Iasi 87
+Hirsova 151 Urziceni 98 Eforie 86
+Eforie 161 Hirsova 86

20151209/src/enshu_20151209/src/a_star.cpp

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+#include <iostream>
+#include <fstream>
+#include <sstream>
+#include <vector>
+#include <map>
+#include <string>
+#include <algorithm>
+
+using namespace std;
+
+class city
+{
+public:
+  string name;
+  int dist;
+  map<string, int> nextto;
+  int cost = -1;
+  int checked = 0;
+  string prev = "";
+  city(string name, int dist){
+    this->name = name;
+    this->dist = dist;
+  }
+  ~city(){}
+
+  void addcity(string nextname, int nextdist){
+    this->nextto.insert(map<string, int>::value_type(nextname, nextdist));
+  }
+
+};
+
+
+void readfile(string src, map<string, city*>& citylist){
+  ifstream ifs(src.c_str());
+  string line;
+  stringstream ssline;
+  while(ifs && getline(ifs, line)){
+    if(line.find('#') == 0){
+      continue;
+    }
+    ssline.str("");
+    ssline.clear(stringstream::goodbit);
+    ssline.str(line);
+
+    stringstream sstmp;
+    string name;
+    string nextname;
+    string tmp;
+    int dist;
+    city* citytmp;
+    getline(ssline, name, ' ');
+    getline(ssline, tmp, ' ');
+    sstmp.str(tmp);
+    sstmp >> dist;
+    citytmp = new city(name, dist);
+    while(getline(ssline, nextname, ' ')){
+      getline(ssline, tmp, ' ');
+      sstmp.str("");
+      sstmp.clear(stringstream::goodbit);
+      sstmp.str(tmp);
+      sstmp >> dist;
+      citytmp->addcity(nextname, dist);
+    }
+    citylist.insert(pair<string, city*>(name, citytmp));
+  }
+}
+
+city* a_star_search(map<string, city*>& citylist, string startcity){
+  vector<city*> stack;
+  city* popcity;
+  stack.push_back(citylist[startcity]);
+  citylist[startcity]->checked = 1;
+  citylist[startcity]->cost = 0;
+
+  while(stack.size()){
+    //A*でソート(評価関数が最小のものを末尾へ)
+    sort(stack.begin(), stack.end(), [](const city* x, const city* y){return (y->cost + y->dist) -(x->cost + x->dist);});
+    //スタックの末尾取り出し
+    popcity = stack.back();
+    stack.pop_back();
+    //ゴールかどうかチェック
+    if(popcity->dist == 0){
+      return popcity;
+    }
+    //周りをスタックに入れる
+    for(map<string, int>::iterator itr = popcity->nextto.begin(); itr != popcity->nextto.end(); itr++){
+      if(citylist[itr->first]->checked == 0){
+	citylist[itr->first]->checked = 1;
+	citylist[itr->first]->cost = popcity->cost + itr->second;
+	citylist[itr->first]->prev = popcity->name;
+	stack.push_back(citylist[itr->first]);
+      }
+    }
+  }
+  //ゴールを見つける前にスタックが空になった場合
+  return NULL;
+}
+
+void trackback(map<string, city*> citylist, city* goal, string startcity){
+  vector<city*> route;
+  city* cityptr = goal;
+  while(true){
+    route.push_back(cityptr);
+    if(cityptr->prev == ""){
+      break;
+    }
+    cityptr = citylist[cityptr->prev];
+  }
+  reverse(route.begin(), route.end());
+
+  //結果表示
+  for(vector<city*>::iterator itr = route.begin(); itr != route.end(); itr++){
+    cout << (*itr)->name << endl;
+  }
+}
+
+int main(){
+  map<string, city*> citylist;
+  readfile("../data/romania2.dat", citylist);
+
+  string startcity = "Oradea";
+  city* goal = a_star_search(citylist, startcity);
+  if(goal == NULL){
+    cout << "Couldn't find the goal" << endl;
+  }else{
+    trackback(citylist, goal, startcity);
+  }
+  return 0;
+}