【HDU】1540 Tunnel Warfare

  1 #include<cstdio>

  2 #include<stack>

  3 #define MAXN 50010

  4 #define MAX(a,b) ((a)>(b)?(a):(b))

  5 using namespace std;

  6 stack<int>st;

  7 struct node

  8 {

  9     int left,right;

 10 };

 11 node tree[MAXN<<2];

 12 void Build(int L,int R,int rt)

 13 {

 14     tree[rt].left=tree[rt].right=R-L+1;

 15     if(L!=R)

 16     {

 17         int mid=(L+R)>>1;

 18         Build(L,mid,rt<<1);

 19         Build(mid+1,R,rt<<1|1);

 20     }

 21 }

 22 inline void PushUp(int mid,int L,int R,int rt)

 23 {

 24     tree[rt].left=tree[rt<<1].left;

 25     tree[rt].right=tree[rt<<1|1].right;

 26     if(tree[rt].left==mid-L+1)

 27         tree[rt].left+=tree[rt<<1|1].left;

 28     if(tree[rt].right==R-mid)

 29         tree[rt].right+=tree[rt<<1].right;

 30 }

 31 void Update(int x,int val,int L,int R,int rt)

 32 {

 33     if(L==R)

 34         tree[rt].left=tree[rt].right=val;

 35     else

 36     {

 37         int mid=(L+R)>>1;

 38         if(x<=mid)

 39             Update(x,val,L,mid,rt<<1);

 40         else

 41             Update(x,val,mid+1,R,rt<<1|1);

 42         PushUp(mid,L,R,rt);

 43     }

 44 }

 45 int Query(int x,int L,int R,int rt)

 46 {

 47     if(L==R)

 48         return tree[rt].left;

 49     int mid=(L+R)>>1;

 50     if(x<=mid)

 51     {

 52         if(tree[rt<<1].left==mid-L+1)

 53             return tree[rt<<1].left+tree[rt<<1|1].left;

 54         else if(L+tree[rt<<1].left>x)

 55             return tree[rt<<1].left;

 56         else if(x>mid-tree[rt<<1].right)

 57             return tree[rt<<1].right+tree[rt<<1|1].left;

 58         else

 59             return Query(x,L,mid,rt<<1);

 60     }

 61     else

 62     {

 63         if(tree[rt<<1|1].right==R-mid)

 64             return tree[rt<<1|1].right+tree[rt<<1].right;

 65         else if(x<mid+1+tree[rt<<1|1].left)

 66             return tree[rt<<1].right+tree[rt<<1|1].left;

 67         else if(x>R-tree[rt<<1|1].right)

 68             return tree[rt<<1|1].right;

 69         else

 70             return Query(x,mid+1,R,rt<<1|1);

 71     }

 72 }

 73 int main()

 74 {

 75     int n,m,x;

 76     char ch;

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

 78     {

 79         Build(1,n,1);

 80         for(;!st.empty();st.pop());

 81         while(m--)

 82         {

 83             scanf(" %c",&ch);

 84             if(ch=='D')

 85             {

 86                 scanf("%d",&x);

 87                 st.push(x);

 88                 Update(x,0,1,n,1);

 89             }

 90             else if(ch=='Q')

 91             {

 92                 scanf("%d",&x);

 93                 printf("%d\n",Query(x,1,n,1));

 94             }

 95             else

 96             {

 97                 if(!st.empty())

 98                 {

 99                     Update(st.top(),1,1,n,1);

100                     st.pop();

101                 }

102             }

103         }

104     }

105     return 0;

106 }