POI2012

  1 #include <cstdio>
  2 const int sizeOfPoint=500005;
  3 const int sizeOfEdge=500005;
  4 
  5 inline int lg(int);
  6 inline int min(int, int);
  7 inline int max(int, int);
  8 inline void swap(int & , int & );
  9 inline int getint();
 10 inline void putint(int);
 11 
 12 struct edge {int point; edge * next;};
 13 edge memory[sizeOfEdge], * port=memory;
 14 inline edge * newedge(int, edge * );
 15 
 16 struct node {int x, y; inline node(int=0, int=0);};
 17 inline bool operator < (node, node);
 18 
 19 int n, m, k;
 20 int p[sizeOfPoint];
 21 edge * e[sizeOfPoint];
 22 int a[32][sizeOfPoint];
 23 int g[sizeOfPoint], s[sizeOfPoint];
 24 int f[sizeOfPoint], d[sizeOfPoint];
 25 int l[sizeOfPoint];
 26 bool v[sizeOfPoint], b[sizeOfPoint];
 27 inline void bfs(int);
 28 inline int lca(int, int);
 29 
 30 int main()
 31 {
 32     n=getint(), k=getint();
 33     for (int i=1;i<=n;i++)
 34     {
 35         p[i]=getint();
 36         e[p[i]]=newedge(i, e[p[i]]);
 37     }
 38 
 39     for (int i=1;i<=n;i++) if (!v[i])
 40     {
 41         int u=i;
 42         for ( ;!b[u];u=p[u]) b[u]=true;
 43 
 44         ++m;
 45         for (int j=1;!l[u];j++, u=p[u])
 46         {
 47             g[u]=m;
 48             s[m]++;
 49             l[u]=j;
 50             bfs(u);
 51         }
 52     }
 53 
 54     for (int i=1;i<=k;i++)
 55     {
 56         int a=getint(), b=getint();
 57 
 58         if (g[f[a]]!=g[f[b]])
 59         {
 60             putint(-1), putchar(‘ ‘);
 61             putint(-1), putchar(‘\n‘);
 62         }
 63         else if (f[a]==f[b])
 64         {
 65             int c=lca(a, b);
 66             putint(d[a]-d[c]), putchar(‘ ‘);
 67             putint(d[b]-d[c]), putchar(‘\n‘);
 68         }
 69         else
 70         {
 71             int o=s[g[f[a]]];
 72             node ans1=node(d[a], d[b]), ans2=node(d[a], d[b]);
 73 
 74             if (l[f[a]]<l[f[b]])
 75             {
 76                 ans1.x+=l[f[b]]-l[f[a]];
 77                 ans2.y+=o-(l[f[b]]-l[f[a]]);
 78             }
 79             else
 80             {
 81                 ans1.x+=o-(l[f[a]]-l[f[b]]);
 82                 ans2.y+=l[f[a]]-l[f[b]];
 83             }
 84 
 85             if (ans1<ans2)
 86             {
 87                 putint(ans1.x), putchar(‘ ‘);
 88                 putint(ans1.y), putchar(‘\n‘);
 89             }
 90             else
 91             {
 92                 putint(ans2.x), putchar(‘ ‘);
 93                 putint(ans2.y), putchar(‘\n‘);
 94             }
 95         }
 96     }
 97 
 98     return 0;
 99 }
100 
101 inline int lg(int x)
102 {
103     return 31-__builtin_clz(x);
104 }
105 inline int min(int x, int y)
106 {
107     return x<y?x:y;
108 }
109 inline int max(int x, int y)
110 {
111     return x>y?x:y;
112 }
113 inline void swap(int & x, int & y)
114 {
115     int t=x; x=y; y=t;
116 }
117 inline int getint()
118 {
119     register int num=0;
120     register char ch;
121     do ch=getchar(); while (ch<‘0‘ || ch>‘9‘);
122     do num=num*10+ch-‘0‘, ch=getchar(); while (ch>=‘0‘ && ch<=‘9‘);
123     return num;
124 }
125 inline void putint(int num)
126 {
127     char stack[11];
128     register int top=0;
129     if (num==0) stack[top=1]=‘0‘;
130     if (num<0) putchar(‘-‘), num=-num;
131     for ( ;num;num/=10) stack[++top]=num%10+‘0‘;
132     for ( ;top;top--) putchar(stack[top]);
133 }
134 
135 inline edge * newedge(int point, edge * next)
136 {
137     edge * ret=port++;
138     ret->point=point; ret->next=next;
139     return ret;
140 }
141 
142 inline node::node(int _x, int _y)
143 {
144     x=_x;
145     y=_y;
146 }
147 inline bool operator < (node a, node b)
148 {
149     if (max(a.x, a.y)<max(b.x, b.y)) return true;
150     if (max(a.x, a.y)>max(b.x, b.y)) return false;
151     if (min(a.x, a.y)<min(b.x, b.y)) return true;
152     if (min(a.x, a.y)>min(b.x, b.y)) return false;
153     return a.y<b.y;
154 }
155 
156 inline void bfs(int root)
157 {
158     static int q[sizeOfPoint];
159     int s=0, t=0;
160     d[root]=0;
161     f[root]=root;
162 
163     for (q[t++]=root;s<t;s++)
164     {
165         int u=q[s];
166         v[u]=true;
167         if (d[u]>1)
168         {
169             int lim=lg(d[u]);
170             for (int i=1;i<=lim;i++)
171                 a[i][u]=a[i-1][a[i-1][u]];
172         }
173 
174         for (edge * i=e[u];i;i=i->next) if (i->point!=p[u] && !l[i->point])
175         {
176             d[i->point]=d[u]+1;
177             f[i->point]=root;
178             a[0][i->point]=u;
179             q[t++]=i->point;
180         }
181     }
182 }
183 inline int lca(int u, int v)
184 {
185     int dist;
186     if (d[u]<d[v]) swap(u, v);
187     while ((dist=d[u]-d[v])) u=a[__builtin_ctz(dist)][u];
188     if (u==v) return u;
189     for (int i=31;i>=0;i--)
190         if (a[i][u]!=a[i][v])
191             u=a[i][u],
192             v=a[i][v];
193     return a[0][u];
194 }