CF 46D Parking Lot

CF_46D

    由于数据范围很小，实际上可以直接暴力的。但为了练练线段树合并区间的操作所以就用线段树写了。

    更多和线段树合并区间有关的题目可以参考胡浩的博客：http://www.notonlysuccess.com/index.php/segment-tree-complete/。

#include<stdio.h>
#include<string.h>
#define MAXD 100210
#define MAXQ 110
int N, L, B, F, lc[4 * MAXD], mc[4 * MAXD], rc[4 * MAXD], to[4 * MAXD];
struct Car
{
    int x, y;
}car[MAXQ];
void build(int cur, int x, int y)
{
    int mid = (x + y) >> 1, ls = cur << 1, rs = (cur << 1) | 1;
    mc[cur] = lc[cur] = rc[cur] = y - x + 1;
    to[cur] = -1;
    if(x == y)
        return ;
    build(ls, x, mid);
    build(rs, mid + 1, y);
}
int getmax(int x, int y)
{
    return x > y ? x : y;
}
void update(int cur, int x, int y)
{
    int mid = (x + y) >> 1, ls = cur << 1, rs = (cur << 1) | 1;
    mc[cur] = getmax(mc[ls], mc[rs]);
    mc[cur] = getmax(rc[ls] + lc[rs], mc[cur]);
    lc[cur] = lc[ls] + (lc[ls] == mid - x + 1 ? lc[rs] : 0);
    rc[cur] = rc[rs] + (rc[rs] == y - mid ? rc[ls] : 0);
}
void pushdown(int cur, int x, int y)
{
    int mid = (x + y) >> 1, ls = cur << 1, rs = (cur << 1) | 1;
    if(to[cur] != -1)
    {
        to[ls] = to[rs] = to[cur];
        mc[ls] = lc[ls] = rc[ls] = (to[cur] ? 0 : mid - x + 1);
        mc[rs] = lc[rs] = rc[rs] = (to[cur] ? 0 : y - mid);
        to[cur] = -1;
    }
}
int query(int cur, int x, int y, int z)
{
    int mid = (x + y) >> 1, ls = cur << 1, rs = (cur << 1) | 1;
    if(x == y)
        return x;
    pushdown(cur, x, y);
    if(mc[rs] >= z)
        return query(rs, mid + 1, y, z);
    else if(rc[ls] + lc[rs] >= z)
        return mid + lc[rs];
    else
        return query(ls, x, mid, z);
}
void refresh(int cur, int x, int y, int s, int t, int c)
{
    int mid = (x + y) >> 1, ls = cur << 1, rs = (cur << 1) | 1;
    if(x >= s && y <= t)
    {
        to[cur] = c;
        mc[cur] = lc[cur] = rc[cur] = (c ? 0 : y - x + 1);
        return ;
    }
    pushdown(cur, x, y);
    if(mid >= s)
        refresh(ls, x, mid, s, t, c);
    if(mid + 1 <= t)
        refresh(rs, mid + 1, y, s, t, c);
    update(cur, x, y);
}
void solve()
{
    int i, j, k, x, y, n, len;
    scanf("%d", &n);
    for(i = 1; i <= n; i ++)
    {
        scanf("%d", &j);
        if(j == 1)
        {
            scanf("%d", &len);
            if(mc[1] < len + B + F)
                printf("-1\n");
            else
            {
                y = query(1, 1, N, len + B + F);
                printf("%d\n", N - y);
                car[i].x = y - B - len + 1, car[i].y = y - B;
                refresh(1, 1, N, car[i].x, car[i].y, 1);
            }
        }
        else
        {
            scanf("%d", &k);
            refresh(1, 1, N, car[k].x, car[k].y, 0);
        }
    }
}
void init()
{
    N = L + B + F;
    build(1, 1, N);
}
int main()
{
    while(scanf("%d%d%d", &L, &B, &F) == 3)
    {
        init();
        solve();
    }
    return 0;
}