[BZOJ 2819]Nim

最近都忙的没空写题解了喵～

看到 1= 终于是保住了也算是一个小小的安慰吧 555……

 

湖北省队互测题，据说会爆栈，但 Linux 下 栈空间=内存=128M 真的吃不下？

反正我是写了个人工栈～

这似乎是我近 4 天里写的第 3 道树链剖分？

 

  1 #include <cstdio>

  2 #include <cstring>

  3 #include <cstdlib>

  4 const int sizeOfPoint=500005;

  5 const int sizeOfEdge=1000001;

  6 

  7 int n, m, q;

  8 int w[sizeOfPoint];

  9 int f[sizeOfPoint], d[sizeOfPoint], s[sizeOfPoint];

 10 int num, idx[sizeOfPoint], top[sizeOfPoint], son[sizeOfPoint];

 11 inline char getch();

 12 inline int getint();

 13 inline void putint(int);

 14 

 15 struct edge {int point; edge * next;};

 16 edge memory[sizeOfEdge], * port=memory;

 17 edge * e[sizeOfPoint];

 18 inline edge * newedge(int, edge * );

 19 inline void link(int, int);

 20 

 21 int tot, stack[sizeOfPoint];

 22 edge * t[sizeOfPoint];

 23 inline void dfsTree();

 24 inline void dfsChain();

 25 

 26 int T[sizeOfPoint<<2];

 27 inline void build();

 28 inline void updateItem(int, int);

 29 inline int querySegment(int, int);

 30 

 31 inline void swap(int & , int & );

 32 inline int queryChain(int, int);

 33 

 34 int main()

 35 {

 36     char ch;

 37     int u, v;

 38 

 39     n=getint();

 40     for (int i=1;i<=n;i++)

 41         w[i]=getint();

 42     for (int i=1;i<n;i++)

 43     {

 44         int u=getint(), v=getint();

 45         link(u, v);

 46     }

 47 

 48     dfsTree();

 49     dfsChain();

 50     build();

 51 

 52     q=getint();

 53     for (int i=1;i<=q;i++)

 54     {

 55         ch=getch(), u=getint(), v=getint();

 56 

 57         if (ch=='Q') putint(queryChain(u, v));

 58         else updateItem(idx[u], v);

 59     }

 60 

 61     return 0;

 62 }

 63 inline char getch()

 64 {

 65     register char ch;

 66     do ch=getchar(); while (ch!='Q' && ch!='C');

 67     return ch;

 68 }

 69 inline int getint()

 70 {

 71     register int num=0;

 72     register char ch;

 73     do ch=getchar(); while (ch<'0' || ch>'9');

 74     do num=num*10+ch-'0', ch=getchar(); while (ch>='0' && ch<='9');

 75     return num;

 76 }

 77 inline void putint(int num)

 78 {

 79     if (num>0) putchar('Y'), putchar('e'), putchar('s');

 80     else putchar('N'), putchar('o');

 81     putchar('\n');

 82 }

 83 inline edge * newedge(int point, edge * next)

 84 {

 85     edge * ret=port++;

 86     ret->point=point; ret->next=next;

 87     return ret;

 88 }

 89 inline void link(int u, int v)

 90 {

 91     e[u]=newedge(v, e[u]); e[v]=newedge(u, e[v]);

 92 }

 93 inline void dfsTree()

 94 {

 95     int u;

 96 

 97     memcpy(t, e, sizeof(e));

 98     memset(d, 0xFF, sizeof(d)); d[1]=0;

 99     s[1]=1;

100     for (stack[++tot]=1;tot; )

101     {

102         u=stack[tot];

103 

104         edge *& i=t[u];

105         for ( ;i && d[i->point]>=0;i=i->next);

106         if (i)

107         {

108             stack[++tot]=i->point;

109             f[i->point]=u;

110             d[i->point]=d[u]+1;

111             s[i->point]=1;

112         }

113         else

114         {

115             if (!f[u]) break;

116             s[f[u]]+=s[u];

117             if (s[u]>s[son[f[u]]])

118                 son[f[u]]=u;

119             tot--;

120         }

121     }

122 }

123 inline void dfsChain()

124 {

125     int u;

126 

127     memcpy(t, e, sizeof(e));

128     idx[1]=num=1; top[1]=1;

129     for (stack[++tot]=1;tot; )

130     {

131         u=stack[tot];

132         if (son[u] && !idx[son[u]])

133         {

134             stack[++tot]=son[u];

135             idx[son[u]]=++num;

136             top[son[u]]=top[u];

137             continue;

138         }

139 

140         edge *& i=t[u];

141         for ( ;i && idx[i->point];i=i->next);

142         if (i)

143         {

144             stack[++tot]=i->point;

145             idx[i->point]=++num;

146             top[i->point]=i->point;

147         }

148         else

149         {

150             if (!f[u]) break;

151             tot--;

152         }

153     }

154 }

155 inline void build()

156 {

157     for (m=1;m<n+2;m<<=1);

158     for (int i=1;i<=n;i++) T[idx[i]+m]=w[i];

159     for (int i=m;i>=1;i--) T[i]=T[i<<1]^T[i<<1|1];

160 }

161 inline void updateItem(int i, int t)

162 {

163     for (T[i+=m]=t, i>>=1;i;i>>=1) T[i]=T[i<<1]^T[i<<1|1];

164 }

165 inline int querySegment(int l, int r)

166 {

167     int sum=0;

168     for (l=l+m-1, r=r+m+1;l^r^1;l>>=1, r>>=1)

169     {

170         if (~l&1) sum^=T[l^1];

171         if ( r&1) sum^=T[r^1];

172     }

173     return sum;

174 }

175 inline void swap(int & u, int & v)

176 {

177     int t=u; u=v; v=t;

178 }

179 inline int queryChain(int u, int v)

180 {

181     int sum=0;

182     while (top[u]!=top[v])

183     {

184         if (d[top[u]]<d[top[v]]) swap(u, v);

185         sum^=querySegment(idx[top[u]], idx[u]);

186         u=f[top[u]];

187     }

188     if (d[u]>d[v]) swap(u, v);

189     sum^=querySegment(idx[u], idx[v]);

190     return sum;

191 }

1A 好评如潮