【POJ1417】【带标记并查集+DP】True Liars

  1 #include <iostream>
  2 #include <cstdio>
  3 #include <algorithm>
  4 #include <cstring>
  5 #include <vector>
  6 #include <utility>
  7 #include <iomanip>
  8 #include <string>
  9 #include <cmath>
 10 #include <queue>
 11 #include <map>
 12 #define LOCAL
 13 const int MAXN = 1000 + 10; 
 14 const int MAX = 30000 + 10; 
 15 using namespace std;
 16 struct DATA{
 17        int a, b;
 18 }data[MAXN];
 19 int n, p1, p2, q;
 20 int parent[MAXN] ,val[MAXN];
 21 int num[MAXN];//num[i]代表如果i是并查集中的根，那么他在AB表中的位置就num[i] 
 22 int f[MAXN][MAXN], cnt; 
 23 int pre[MAXN][MAXN];//DP中记录状态转移过来的位置 
 24 int Ans[MAXN];//表示答案中被选为好人或者不是好人 
 25 
 26 int find(int x){
 27     int f = x, tmp = 0;
 28     while (x != parent[x]){
 29           tmp += val[x];
 30           x = parent[x];
 31     }
 32     parent[f] = x;
 33     val[f] = tmp % 2;
 34     return x;
 35 }
 36 
 37 void init(){
 38      n = p1 + p2;//即总的人数 
 39      //val为0代表相同集合，1代表不同的集合 
 40      for (int i = 1; i <= n; i++){
 41          val[i] = 0;
 42          parent[i] = i; 
 43      }
 44      for (int i = 1; i <= q; i++){
 45          int x, y;
 46          char str[5];
 47          scanf("%d%d", &x, &y);
 48          scanf("%s", str);
 49          if (find(x) == find(y)) continue;//在同一个集合之内就不用考虑了 
 50          else{
 51               if (str[0] == ‘y‘){ //一定是一种集合之内 
 52                  int xx = find(x), yy = find(y);
 53                  parent[xx] = y;
 54                  val[xx] = (-val[x] + 2) % 2;
 55               }else{
 56                  int xx = find(x), yy = find(y);
 57                  parent[xx] = y;
 58                  val[xx] = (-val[x] + 3) % 2; 
 59               }
 60          }
 61      }
 62 }
 63 //计算出各个并查集的同类和不同类 
 64 void prepare(){
 65      memset(data, 0, sizeof(data));
 66      cnt = 0;
 67      for (int i = 1; i <= n; i++){
 68          if (parent[i] != i) continue;
 69          num[i] = ++cnt;
 70      }
 71      for (int i = 1; i <= n; i++){
 72          int xx = find(i);
 73          if (val[i] == 0) data[num[xx]].a++;//和它同一类
 74          else data[num[xx]].b++;//不同类 
 75      }
 76 }
 77 void dp(){
 78      memset(f, 0, sizeof(f));
 79      //f[i][j]表示到了第i个好人有j个的时候的方案数量,注意只要保存3个量就可以了 
 80      f[0][0] = 1;
 81      for (int i = 1; i <= cnt; i++)
 82      for (int j = p1; j >=0; j--){
 83          if (j - data[1].a >= 0) f[i][j] += f[i - 1][j - data[i].a];
 84          if (j - data[1].b >= 0) f[i][j] += f[i - 1][j - data[i].b];
 85          if (f[i][j] >= 2)  f[i][j] = 2;//不要做太大了 
 86          if (f[i][j] == 1){//有解
 87             if (j - data[i].a >= 0 && f[i - 1][j - data[i].a] == 1) pre[i][j] = 0;//a类选为好人 
 88             if (j - data[i].b >= 0 && f[i - 1][j - data[i].b] == 1) pre[i][j] = 1;//b类选为好人 
 89          }
 90      } 
 91      if (f[cnt][p1] != 1){printf("no\n");return;}
 92      int last = p1;
 93      for (int i = cnt; i >= 1; i--){
 94          Ans[i] = pre[i][last];
 95          if (Ans[i] == 0) last -= data[i].a;
 96          else last -= data[i].b;
 97      }
 98      for (int i = 1; i <= n; i++){
 99          int xx = find(i);
100          if (Ans[num[xx]] == 1 && val[i] == 1) printf("%d\n", i);            
101          if (Ans[num[xx]] == 0 && val[i] == 0) printf("%d\n", i);
102      }
103      printf("end\n");
104 } 
105  
106 int main(){
107     int T;
108     #ifdef LOCAL
109     freopen("data.txt",  "r",  stdin);
110     freopen("out.txt",  "w",  stdout); 
111     #endif
112     while (scanf("%d%d%d", &q, &p1, &p2)){
113           if (q == 0 && p1 == 0 && p2 == 0) break;
114           init();
115           prepare();
116           dp();
117           //printf("%d", data[1].b); 
118     }
119     return 0;
120 }