【HDU1272】小希的迷宫（并查集基础题）

仍旧裸敲并查集。有这两点注意：

1.输入 0 0 时候要输出YES

2.留心数组的初始化

 #include <iostream>
 #include <cstring>
 #include <cstdlib>
 #include <cstdio>
 #include <numeric>
 #include <algorithm>
 #include <cctype>
 #include <string>

 using namespace std;

 const int MAXN = ;

 bool flag[MAXN];
 int connectedList[MAXN];
 bool isOk = true;
 int nStart, nEnd;

 void Init() {
     for (int i = ; i < MAXN; ++i) {
         connectedList[i] = i;
         flag[i] = false;
     }
 }

 int getFather(int vetex) {
     int pos = vetex;
     while(pos != connectedList[pos]) {
         pos = connectedList[pos];
     }
     return pos;
 }

 int countListNum() {
     int count = ;
     for (int i = ; i < MAXN; ++i) {
         if (flag[i] == true) {
             if (getFather(i) == i) {
                 ++count;
             }
         }
     }
     return count;
 }

 void process() {
     if( getFather(nStart) == getFather(nEnd)) {
         isOk = false;
         return;
     }
     if( getFather(nStart) == nStart && getFather(nEnd) == nEnd) {
         connectedList[nEnd] = nStart;
     } else if(getFather(nStart) == nStart) {
         connectedList[nStart] = getFather(nEnd);
     } else {
         connectedList[nEnd] = getFather(nStart);
     }
     flag[nStart] = true;
     flag[nEnd] = true;
 }
 int main() {
     while(cin >> nStart >> nEnd) {
         if(nStart == - && nEnd == -) break;
         if(nStart || nEnd) {
             isOk = true;
             memset(flag, false , sizeof(flag));
             Init();
             process();

             while(cin >> nStart >> nEnd, nStart || nEnd) {
                 if(isOk == true) {
                     process();
                 }
             }

             if(isOk == true) {
                 int count = ;
                 count = countListNum();
                 if(count > ) {
                     isOk = false;
                 }
             }
         } else {
             isOk = true;
         }
         if(isOk == false) {
             cout << "No" << endl;
         } else {
             cout << "Yes" << endl;
         }
     }
     return ;
 }