UVa-511-Way to SanJose?

    map<string,map<double,vector<string>,greater<double>>>是每一个地点到包含这些地点的地图的映射。第二个map是地图面积到地图的映射，其中传入了一个greater<double>来讲这些面积按照从大到下的顺序排序，对应detail level 从小到大。vector<string> 保存了面积相同的地图，在程序中，我定义了一个compare函数来将这些面积相同的地图按照题目要求排序，这样，vector[0]就是所要找的地图。

    另外需注意的是，题目只说了输入的表示地图的两个点是对角线上的两个点，但并未说是哪一条对角线。

   

#include <iostream>#include <map>#include <vector>#include <string>#include <algorithm>#include <sstream>#include <cmath>#include <functional>using namespace std;struct  Map{Map() = default;Map(double, double, double, double);double x1, y1, x2, y2;double area;pair<double,double> center;};Map::Map(double a, double b, double c, double d){x1 = a;y1 = b;x2 = c;y2 = d;area = (x1 - x2)*(y1 - y2);double x, y;x = (x1 + x2) / 2;y = (y1 + y2) / 2;center = make_pair(x, y);}map<string, map<double, vector<string>,greater<double>>> level;map<string, Map> mapInfo;bool isWithin(double x, double y, Map &m){return x >= m.x2 && x <= m.x1 && y >= m.y2 && y <= m.y1;}double distance1(pair<double, double> &p1, pair<double, double> &p2){return pow(abs(p1.first - p2.first), 2.0) + pow(abs(p1.second - p2.second), 2.0);}bool compare(string &s1, string &s2,pair<double,double> &p){Map map1 = mapInfo[s1], map2 = mapInfo[s2];double d1 = distance1(map1.center, p), d2 = distance1(map2.center, p);if (d1 != d2)return d1 < d2;double ratio1 = (map1.y1 - map1.y2) / (map1.x1 - map1.x2);double ratio2 = (map2.y1 - map2.y2) / (map2.x1 - map2.x2);if (ratio1 != ratio2)return abs(ratio1 - 0.75) < abs(ratio2 - 0.75);pair<double, double> p1(map1.x1, map1.y2);pair<double, double> p2(map2.x1, map2.y2);double d3 = distance1(p1, p);double d4 = distance1(p2, p);if (d3 != d4) return d1>d2;return map1.x2 < map2.x2;}int main(){string line;getline(cin, line);while (getline(cin, line) && line != "LOCATIONS"){string name;double x1, y1, x2, y2;istringstream stream(line);stream >> name >> x1 >> y1 >> x2 >> y2;if (x1 < x2)swap(x1, x2);if (y1 < y2)swap(y1, y2);mapInfo[name] = Map(x1, y1, x2, y2);}while (getline(cin, line) && line != "REQUESTS"){istringstream stream(line);string name;double x, y;stream >> name >> x >> y;for (auto &m : mapInfo){if (isWithin(x, y, m.second))level[name][m.second.area].push_back(m.first);}for (auto &m : level[name])  //m是pair<double,vector<string>>{vector<string> temp(m.second);pair<double, double> p(x, y);sort(temp.begin(), temp.end(), bind(compare, placeholders::_1, placeholders::_2, p));}}while (getline(cin, line) && line != "END"){istringstream stream(line);string name;int n;stream >> name >> n;if (!level.count(name)){cout << name << " at detail level " << n << " unknown location" << endl;continue;}auto m = level[name];if (level[name].empty())cout << name << " " << "at" << " " << "detail level " << n << " no map contains that location" << endl;else{int i = 1;bool flag = false;string temp; for (auto it = m.begin(); it != m.end(); ++it,++i){if (i == n){cout << name << " at detail level " << n << " using " << it->second[0]<<endl;flag = true;}if (i == m.size())temp = it->second[0];}if (!flag)cout << name << " at detail level " << n << " no map at that detail level; using " << temp << endl;}}}