1034. Head of a Gang (30)

分析：

　　考察并查集，注意中间合并时的时间的合并和人数的合并。

  1 #include <iostream>

  2 #include <stdio.h>

  3 #include <algorithm>

  4 #include <cstring>

  5 #include <string>

  6 #include <vector>

  7 #include <cctype>

  8 #include <map>

  9 

 10 using namespace std;

 11 

 12 const int Max_Int = 0x7fffffff;

 13 const int Max_required = 500;

 14 

 15 struct Node                    //记录gang的信息

 16 {

 17     int total_person;        //gang中总人数

 18     int time_length;        //gang中总时间

 19     int tree;                //并查集用处

 20 }gang[2005];            

 21 

 22 struct Name

 23 {

 24     char ch[5];

 25 };

 26 

 27 map<string, int> Map_Name2int;        //名字转下标之用

 28 map<int, string> Map_int2Name;

 29 int _index;

 30 

 31 int perp[2005];        //记录每个人花的时间

 32 

 33 void Init()

 34 {

 35     Map_Name2int.clear();

 36     _index = 0;

 37     for (int i = 0; i <= 2000; i++)

 38     {

 39         gang[i].total_person = 1;

 40         gang[i].tree = i;

 41         gang[i].time_length = 0;

 42         perp[i] = 0;

 43     }

 44 }

 45 

 46 

 47 int string2index(string name)

 48 {

 49     map<string, int>::iterator iter = Map_Name2int.find(name);

 50     if (iter != Map_Name2int.end())

 51         return iter->second;

 52     Map_Name2int.insert(make_pair(name, _index));

 53     Map_int2Name.insert(make_pair(_index, name));

 54     _index++;

 55 

 56     return _index - 1;

 57 }

 58 

 59 int get_root(int r)

 60 {

 61     while (r != gang[r].tree)

 62         r = gang[r].tree;

 63     return r;

 64 }

 65 

 66 //-------------------------------------------------

 67 void merge(int fir, int sec, int time)  //合并操作。

 68 {

 69     fir = get_root(fir);

 70     sec = get_root(sec);

 71 

 72     if (fir != sec)                    //如果两个拥有不同的根

 73     {

 74         gang[sec].tree = fir;

 75         gang[fir].time_length += time + gang[sec].time_length;

 76         gang[fir].total_person += gang[sec].total_person;

 77     }

 78     else 

 79         gang[fir].time_length += time;

 80     //cout << gang[fir].total_person << " " << gang[fir].time_length << endl;

 81 }

 82 

 83     

 84 struct Gang                 //以root为首的群的head，存储答案

 85 {

 86     int head;

 87     int root;

 88     string name;

 89 }gang_head[1000];

 90 int total_gang;

 91 

 92 void find_head(int k)

 93 {

 94     total_gang = 0;

 95     for (int i = 0; i < _index; i++)

 96     {

 97         int r = get_root(i);

 98 

 99         //cout << r << " " << Map_int_Name.find(i)->second << endl;

100 

101         if (gang[r].total_person > 2 && gang[r].time_length > k)

102         {

103             bool flag = 0;

104             for (int j = 0; j < total_gang; j++)

105             {

106                 if (gang_head[j].root == r)

107                 {

108                     flag = 1;

109                     if (perp[gang_head[j].head] < perp[i])

110                         gang_head[j].head = i;

111                     break;

112                 }

113             }

114 

115             if (flag == 0)

116             {

117                 gang_head[total_gang].head = i;

118                 gang_head[total_gang].root = r;

119                 total_gang++;

120             }

121         }

122     }

123 }

124 

125 int cmp(const Gang &a, const Gang &b)

126 {

127     return a.name < b.name;

128 }

129 

130 void print_info()

131 {

132     for (int i = 0; i < total_gang; i++)

133         gang_head[i].name = Map_int2Name.find(gang_head[i].head)->second;

134 

135     sort(gang_head, gang_head + total_gang, cmp);

136 

137     printf("%d\n", total_gang);

138     for (int i = 0; i < total_gang; i++)

139     {

140         cout << gang_head[i].name << " " << gang[gang_head[i].root].total_person << endl;

141     }

142 

143 }

144 

145 int main()

146 {

147     int n, k;

148 

149     while (scanf("%d%d", &n, &k) != EOF)

150     {

151 

152         Init();                //初始化

153 

154         string name1, name2;

155         int time;

156         while (n--)

157         {

158             cin >> name1 >> name2 >> time;

159             int fir = string2index(name1);

160             int sec = string2index(name2);

161 

162             perp[fir] += time;

163             perp[sec] += time;

164             merge(fir, sec, time);

165         } 

166 

167         find_head(k);

168 

169         print_info();

170     }

171     return 0;

172 }

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