1034. Head of a Gang

考察并查集。发现并查集什么都不会呀。。。

查看了大神的代码感觉自己太弱了 http://blog.csdn.net/sunbaigui/article/details/8657148

代码照抄的 就是注释了下。留着当笔记吧。 学习了下map set 迭代器 的使用 还是有点不熟练，还要多练。。

感觉这里开始PAT题的类型突然变了。。

#include <iostream>#include <string>#include <vector>#include <map>#include <set>#include <algorithm>#define MAX 1010using namespace std;struct Call {string p1, p2;int time;};struct Node {int weight, parent;};struct Gang {int head, num, sum, maxw;Gang() { head = -1; num = 0; sum = 0; maxw = -1; }};vector <Call> list;vector <Node> p; //并查集set <string> name;map <string, int> str2int;map <int, string> int2str;int NameNum;int N, threthold;void InitSet() {p.resize(NameNum);for (int i = 0; i < NameNum; i++) {p[i].parent = i; p[i].weight = 0; //当父母为自己时为根节点}}//结点压缩//① ①//|   /   \//②   压缩成 ②③//|//③void CompressSet(int top, int x) { //路径压缩    if (top != p[x].parent) {//不是并查集的根结点CompressSet(top, p[x].parent); //继续压缩p[x].parent = top;}}int FindSet(int x) {//查找根节点if (x != p[x].parent) { //不是根结点int top = FindSet(p[x].parent); //top为根结点CompressSet(top, x); //压缩结点}return p[x].parent;//返回根节点}void UnionSet(int x, int y) {int a = FindSet(x);int b = FindSet(y);p[a].parent = b;}bool cmp(Gang g1, Gang g2) {return int2str[g1.head] < int2str[g2.head];}int main() {cin >> N >> threthold;Call temp;for (int i = 0; i < N; i++) {cin >> temp.p1 >> temp.p2 >> temp.time;list.push_back(temp);name.insert(temp.p1);name.insert(temp.p2);}NameNum = name.size();//名字转换为编号set<string>::iterator it;int id = 0;for (it = name.begin(); it != name.end(); it++, id++) {str2int[*it] = id;int2str[id] = *it;}InitSet();for(int i = 0; i < list.size(); i++){int u = str2int[list[i].p1];int v = str2int[list[i].p2];p[u].weight += list[i].time;p[v].weight += list[i].time;UnionSet(u, v);}#ifdef _DEBUGfor (int i = 0; i < p.size(); i++) {cout << int2str[i] << " " << int2str[p[i].parent] << " " << int2str[FindSet(i)] << endl;}#endifmap <int, Gang> allset; // fitst = int second = Gangmap <int, Gang>::iterator it2;for (int i = 0; i < NameNum; i++) {int top = FindSet(i);it2 = allset.find(top);//查找根节点的帮会集合if (it2 != allset.end()) {allset[top].sum += p[i].weight;allset[top].num++;if (p[i].weight > allset[top].maxw) {allset[top].maxw = p[i].weight;allset[top].head = i;}}else {//没有 新建帮会Gang temp;temp.head = i; temp.maxw = p[i].weight;temp.num = 1; temp.sum = p[i].weight;allset[top] = temp;}}vector <Gang> gang;for (it2 = allset.begin(); it2 != allset.end(); it2++) {if (it2->second.sum > 2 * threthold && it2->second.num > 2)gang.push_back(it2->second);}sort(gang.begin(), gang.end(), cmp);cout << gang.size() << endl;for (int i = 0; i < gang.size(); i++) {cout << int2str[gang[i].head] << " " << gang[i].num << endl;}system("pause");return 0;}