codeforces 46D Parking Lot（线段树 区间合并）

#include <cstdio>
#include <cstring>
#include <algorithm>

#define lson l,m,rt<<1
#define rson m+1,r,rt<<1|1

const int MAXN = 101000;
int lsum[MAXN<<2],rsum[MAXN<<2],msum[MAXN<<2];
int cover[MAXN<<2];

void build(int l,int r, int rt)
{
lsum[rt] = rsum[rt] = msum[rt] = r-l+1;
cover[rt] = -1;
if(l == r) return;
int m = (l+r)>>1;
build(lson);
build(rson);
}

void pushDown(int rt, int len)
{
if(cover[rt] != -1)
{
cover[rt<<1] = cover[rt<<1|1] = cover[rt];
lsum[rt<<1] = rsum[rt<<1] = msum[rt<<1] = cover[rt] ? 0: len-(len>>1);
lsum[rt<<1|1] = rsum[rt<<1|1] = msum[rt<<1|1] = cover[rt] ? 0 : len>>1;
cover[rt] = -1;
}
}

void pushUp(int rt, int len)
{
lsum[rt] = lsum[rt<<1];
rsum[rt] = rsum[rt<<1|1];
if(lsum[rt<<1] == len-(len>>1)) lsum[rt] += lsum[rt<<1|1];
if(rsum[rt<<1|1] == (len>>1)) rsum[rt] += rsum[rt<<1];

msum[rt] = std::max(rsum[rt<<1]+lsum[rt<<1|1],std::max(msum[rt<<1],msum[rt<<1|1]));
}

int query(int l, int r, int rt, int len)
{
if(l == r) return l;
pushDown(rt,r-l+1);
int m = (l+r)>>1;
if(msum[rt<<1] >= len) return query(lson,len);
else if(rsum[rt<<1]+lsum[rt<<1|1] >= len)
return m-rsum[rt<<1]+1;
return query(rson,len);
}

void update(int L, int R, int c, int l, int r , int rt)
{
if(l >= L && r <= R)
{
lsum[rt] = msum[rt] = rsum[rt] = c ? 0:r-l+1;
cover[rt] = c;
return;
}
pushDown(rt,r-l+1);
int m =(l+r)>>1;
if(m  >= L) update(L,R,c,lson);
if(R > m) update(L,R,c,rson);
pushUp(rt,r-l+1);
}

int start[110];
int len[110];
int main()
{
int n,b,f,q,op,x;
scanf("%d %d %d",&n,&b,&f);
build(1,b+n+f,1);
scanf("%d",&q);
for(int i = 1; i <= q; ++i)
{
scanf("%d %d",&op,&x);
if(op == 1)
{
if(b+x+f > msum[1])
{
puts("-1");
continue;
}
int pos = query(1,n+b+f,1,b+x+f);
update(b+pos,b+pos+x-1,1,1,n+b+f,1);
printf("%d\n",pos-1);
start[i] = pos;
len[i] = x;
}
else
update(b+start[x],b+start[x]+len[x]-1,0,1,n+b+f,1);
}
}