POJ - 3667 Hotel （线段树区间合并裸题）

Hotel

Time Limit: 3000MS		Memory Limit: 65536K
Total Submissions: 18289		Accepted: 7937

Description

The cows are journeying north to Thunder Bay in Canada to gain cultural enrichment and enjoy a vacation on the sunny shores of Lake Superior. Bessie, ever the competent travel agent, has named the Bullmoose Hotel on famed Cumberland Street as their vacation residence. This immense hotel has N (1 ≤ N ≤ 50,000) rooms all located on the same side of an extremely long hallway (all the better to see the lake, of course).

The cows and other visitors arrive in groups of size D_i (1 ≤ D_i ≤ N) and approach the front desk to check in. Each group i requests a set of D_i contiguous rooms from Canmuu, the moose staffing the counter. He assigns them some set of consecutive room numbers r..r+D_i-1 if they are available or, if no contiguous set of rooms is available, politely suggests alternate lodging. Canmuu always chooses the value of r to be the smallest possible.

Visitors also depart the hotel from groups of contiguous rooms. Checkout i has the parameters X_i and D_i which specify the vacating of rooms X_i ..X_i +D_i-1 (1 ≤ X_i ≤ N-D_i+1). Some (or all) of those rooms might be empty before the checkout.

Your job is to assist Canmuu by processing M (1 ≤ M < 50,000) checkin/checkout requests. The hotel is initially unoccupied.

Input

* Line 1: Two space-separated integers: N and M
* Lines 2..M+1: Line i+1 contains request expressed as one of two possible formats: (a) Two space separated integers representing a check-in request: 1 and D_i (b) Three space-separated integers representing a check-out: 2, X_i, and D_i

Output

* Lines 1.....: For each check-in request, output a single line with a single integer r, the first room in the contiguous sequence of rooms to be occupied. If the request cannot be satisfied, output 0.

Sample Input

10 6
1 3
1 3
1 3
1 3
2 5 5
1 6

Sample Output

1
4
7
0
5

题意：给出一段长为n的区间，有两种操作：1、查询最靠左并且长度为d的连续区间，并输出其左端点下标；2、清空以l为左端点

长度为d的连续区间

#include <stdio.h>
#include <string.h>
#include <algorithm>
using namespace std;

const int N = 50000 + 10;
int n, m;
struct xx{
    int l, r, lm, rm, m, lazy;
} T[N<<2];

void Pushdown(int k){
    T[k<<1].lazy = T[k<<1|1].lazy = T[k].lazy;
    T[k<<1].lm = T[k<<1].rm = T[k<<1].m = T[k].lazy ? 0 : T[k<<1].r-T[k<<1].l+1;
    T[k<<1|1].lm = T[k<<1|1].rm = T[k<<1|1].m = T[k].lazy ? 0 : T[k<<1|1].r-T[k<<1|1].l+1;
    T[k].lazy = -1;
}

void Pushup(int k){
    T[k].lm = T[k<<1].lm;
    T[k].rm = T[k<<1|1].rm;
    if(T[k].lm == T[k<<1].r-T[k<<1].l+1) T[k].lm += T[k<<1|1].lm;
    if(T[k].rm == T[k<<1|1].r-T[k<<1|1].l+1) T[k].rm += T[k<<1].rm;    T[k].m = max(max(T[k<<1].m, T[k<<1|1].m), T[k<<1].rm+T[k<<1|1].lm);
}

void Build(int l, int r, int k){
    T[k].l = l, T[k].r = r, T[k].lazy = -1;
    T[k].lm = T[k].rm = T[k].m = r-l+1;
    if(l == r) return;
    int mid = (l+r)>>1;
    Build(l, mid, k<<1);
    Build(mid+1, r, k<<1|1);
    Pushup(k);
}

void Update(int l, int r, int v, int k){
    if(l == T[k].l && r == T[k].r){
        T[k].lm = T[k].rm = T[k].m = v ? 0 : T[k].r-T[k].l+1;
        T[k].lazy = v;
        return;
    }
    if(T[k].lazy != -1) Pushdown(k);
    int mid = (T[k].l+T[k].r)>>1;
    if(l <= mid) Update(l, min(mid, r), v, k<<1);
    if(r > mid) Update(max(mid+1, l), r, v, k<<1|1);
    Pushup(k);
}

int Find(int x, int k){
    if(T[k].l == T[k].r) return T[k].l;
    if(T[k].lazy != -1) Pushdown(k);
    int mid = (T[k].l+T[k].r)>>1;
    if(T[k<<1].m >= x) return Find(x, k<<1);
    else if(T[k<<1].rm+T[k<<1|1].lm >= x) return mid-T[k<<1].rm+1;
    else if(T[k<<1|1].m >= x) return Find(x, k<<1|1);
}

int main(){
    while(scanf("%d%d", &n, &m) == 2){
        Build(1, n, 1);
        int op, x, y;;
        for(int i = 0; i < m; i++){
            scanf("%d", &op);
            if(op&1){
                scanf("%d", &x);
                if(T[1].m < x){
                    printf("0\n");
                    continue;
                }
                y = Find(x, 1);
                printf("%d\n", y);
                if(y) Update(y, x+y-1, 1, 1);
            }
            else{
                scanf("%d%d", &x, &y);
                Update(x, x+y-1, 0, 1);
            }
        }
    }
}