POJ3667(线段树区间合并)

#include<cstdio>
#include<algorithm>
#include<cstring>
using namespace std;
#define lson l,m,rt<<1
#define rson m+1,r,rt<<1|1

const int maxn = 50010;
int ls[maxn<<2],rs[maxn<<2],ms[maxn<<2],lazy[maxn<<2];

void pushdown(int rt,int len)
{
    if(~lazy[rt])
    {
        lazy[rt<<1] = lazy[rt<<1|1] = lazy[rt];
        if(lazy[rt])//0,入住
        {
            ms[rt<<1] = ls[rt<<1] = rs[rt<<1] = 0;
            ms[rt<<1|1] = ls[rt<<1|1] = rs[rt<<1|1] = 0;
        }
        else//1,退房
        {
            ms[rt<<1] = ls[rt<<1] = rs[rt<<1] = len-(len>>1);
            ms[rt<<1|1] = ls[rt<<1|1] = rs[rt<<1|1] = len>>1;
        }
        lazy[rt] = -1;
    }
}

void pushup(int rt,int len)
{
    ls[rt] = ls[rt<<1];
    rs[rt] = rs[rt<<1|1];
    if(ls[rt]==len-len/2)
        ls[rt] += ls[rt<<1|1];
    if(rs[rt]==len/2)
        rs[rt] += rs[rt<<1];
    ms[rt] = max(max(ms[rt<<1],ms[rt<<1|1]),ls[rt<<1|1]+rs[rt<<1]);
}


void build(int l,int r,int rt)
{
    ms[rt] = ls[rt] = rs[rt] = r-l+1;
    lazy[rt] = -1;
    if(l==r)
        return ;
    int m = (l+r)>>1;
    build(lson);
    build(rson);
}

void update(int L,int R,int C,int l,int r,int rt)
{
    if(L<=l&&r<=R)
    {
        if(!C)//退房
            ms[rt] = ls[rt] = rs[rt] = (r-l+1);
        else//入住
            ms[rt] = ls[rt] = rs[rt] = 0;
        lazy[rt] = C;
        return ;
    }
    pushdown(rt,r-l+1);
    int m = (l + r)>>1;
    if(L<=m)
        update(L,R,C,lson);
    if(R>m)
        update(L,R,C,rson);
    pushup(rt,r-l+1);
}


int query(int len,int l,int r,int rt)
{
    if(l==r)
        return l;
    pushdown(rt,r-l+1);
    int m = (l+r)>>1;
    if(ms[rt<<1]>=len)
        return query(len,lson);
    else if(ls[rt<<1|1]+rs[rt<<1]>=len)
        return m - rs[rt<<1] + 1;//ls[rt<<1|1]的l
    else
        return query(len,rson);
}

int N,M,op,len,x,y,p;
int main()
{
    scanf("%d%d",&N,&M);
    build(1,N,1);
    while(M--)
    {
        scanf("%d",&op);
        if(op==1)
        {
            scanf("%d",&len);//printf("ms[1]==%d\n",ms[1]);
            if(ms[1]<len)
                printf("0\n");
            else
            {

                p = query(len,1,N,1);
                printf("%d\n",p);
                update(p,p+len-1,1,1,N,1);
            }
        }
        else
        {
            scanf("%d%d",&x,&y);
            update(x,x+y-1,0,1,N,1);
        }
    }
    return 0;
}