UVA11922--Permutation Transformer (伸展树Splay)

题意：m条操作指令，对于指令 a  b 表示取出第a~b个元素，翻转后添加到排列的尾部。

水题卡了一个小时，一直过不了样例。  原来是 dfs输出的时候 忘记向下传递标记了。

  1 #include <cstdio>

  2 #include <cstdlib>

  3 #include <cstring>

  4 #include <algorithm>

  5 using namespace std;

  6 const double eps = 1e-8;

  7 const int maxn = 100086;

  8 int siz[maxn],pre[maxn],ch[maxn][2],rev[maxn],key[maxn];

  9 int n,m,tot,root;

 10 void update_rev(int r)

 11 {

 12     if (!r)

 13         return;

 14     swap(ch[r][0],ch[r][1]);

 15     rev[r] ^= 1;

 16 }

 17 void push_up(int r)

 18 {

 19     siz[r] = siz[ch[r][0]] + siz[ch[r][1]] + 1;

 20 }

 21 void push_down(int r)

 22 {

 23     if (rev[r])

 24     {

 25         update_rev(ch[r][0]);

 26         update_rev(ch[r][1]);

 27         rev[r] = 0;

 28     }

 29 }

 30 void NewNode(int &r,int father,int k)

 31 {

 32     r = ++tot;

 33     pre[r] = father;

 34     ch[r][0] = ch[r][1] = 0;

 35     key[r] = k;

 36     rev[r] = 0;

 37     siz[r] = 1;

 38 }

 39 void build(int &x,int l,int r,int father)

 40 {

 41     if (l > r)

 42         return;

 43     int mid = (l + r) >> 1;

 44     NewNode(x,father,mid);

 45     build(ch[x][0],l,mid-1,x);

 46     build(ch[x][1],mid+1,r,x);

 47     push_up(x);

 48 }

 49 void init()

 50 {

 51     root = tot = 0;

 52     NewNode(root,0,-1);

 53     NewNode(ch[root][1],root,-1);

 54     build(ch[ch[root][1]][0],1,n,ch[root][1]);

 55     push_up(root);

 56     push_up(ch[root][1]);

 57 }

 58 void Rotate(int x,int kind)

 59 {

 60     int y = pre[x];

 61     push_down(y);

 62     push_down(x);

 63     ch[y][!kind] = ch[x][kind];

 64     pre[ch[x][kind]] = y;

 65     if (pre[y])

 66         ch[pre[y]][ch[pre[y]][1] == y] = x;

 67     pre[x] = pre[y];

 68     ch[x][kind] = y;

 69     pre[y] = x;

 70     push_up(y);

 71 }

 72 void Splay(int r,int goal)

 73 {

 74     push_down(r);

 75     while (pre[r] != goal)

 76     {

 77         if (pre[pre[r]] == goal)

 78         {

 79             push_down(pre[r]);

 80             push_down(r);

 81             Rotate(r,ch[pre[r]][0] == r);

 82         }

 83         else

 84         {

 85             int y = pre[r];

 86             int kind = (ch[pre[y]][1] == y);

 87             push_down(pre[y]);

 88             push_down(y);

 89             push_down(r);

 90             if (ch[y][kind] == r)

 91             {

 92                 Rotate(y,!kind);

 93                 Rotate(r,!kind);

 94             }

 95             else

 96             {

 97                 Rotate(r,kind);

 98                 Rotate(r,!kind);

 99             }

100         }

101     }

102     push_up(r);

103     if (goal == 0)

104         root = r;

105 }

106 int Get_kth(int r,int k)

107 {

108     push_down(r);

109     int t = siz[ch[r][0]] + 1;

110     if (k == t)

111         return r;

112     if (k >= t)

113         return Get_kth(ch[r][1],k-t);

114     else

115         return Get_kth(ch[r][0],k);

116 }

117 void Reverse(int u,int v)

118 {

119     Splay(Get_kth(root,u),0);

120     Splay(Get_kth(root,v+2),root);

121     update_rev(ch[ch[root][1]][0]);

122     push_up(ch[root][1]);

123     push_up(root);

124 }

125 void dfs(int r)

126 {

127     if (!r)

128         return;

129     push_down(r);

130     dfs(ch[r][0]);

131     if (r != -1 && key[r] != -1)        //-1设置的虚节点 

132         printf("%d\n",key[r]);

133     dfs(ch[r][1]);

134 }

135 int main(void)

136 {

137     #ifndef ONLINE_JUDGE

138         freopen("in.txt","r",stdin);

139     #endif

140     while (~scanf ("%d%d",&n,&m))

141     {

142         init();

143         for (int i = 0; i < m; i++)

144         {

145             int u,v;

146             scanf ("%d%d",&u,&v);

147             Reverse(u,n);

148             Reverse(u,u+n-v-1);

149         }

150         dfs(root);

151     }

152     return 0;

153 }