poj Hotel

Hotel

Time Limit: 3000MS		Memory Limit: 65536K
Total Submissions: 7782		Accepted: 3299

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

Source

USACO 2008 February Gold

 

分析：线段树：成段替换，区间最大值需要区间合并，成段查询。

#include<cstdio>
#include<cstring>
#define lson l,m,rt<<1
#define rson m+1,r,rt<<1|1

inline int max(int a, int b) {
    return a > b ? a : b;
}
int col[1 << 17], lsum[1 << 17], rsum[1 << 17], msum[1 << 17];

void pushup(int rt, int len) {
    if (lsum[rt << 1] == (len - (len >> 1)))
        lsum[rt] = lsum[rt << 1] + lsum[rt << 1 | 1];
    else
        lsum[rt] = lsum[rt << 1];
    if (rsum[rt << 1 | 1] == (len >> 1))
        rsum[rt] = rsum[rt << 1] + rsum[rt << 1 | 1];
    else
        rsum[rt] = rsum[rt << 1 | 1];
    msum[rt] = max(rsum[rt << 1] + lsum[rt << 1 | 1], max(msum[rt << 1], msum[rt << 1 | 1]));
}

void build(int l, int r, int rt) {
    if (l == r) {
        col[rt] = 0;
        lsum[rt] = rsum[rt] = msum[rt] = 1;
        return;
    }
    int m = (r + l) >> 1;
    build(lson);
    build(rson);
    pushup(rt, r - l + 1);
}

void pushdown(int rt, int len) {
    if (col[rt] == 1) {
        col[rt << 1] = col[rt << 1 | 1] = 1;
        col[rt] = -1;
        lsum[rt << 1] = rsum[rt << 1] = msum[rt << 1] = 0;
        lsum[rt << 1|1] = rsum[rt << 1|1] = msum[rt << 1|1] = 0;
    } else if (col[rt] == 0) {
        col[rt << 1] = col[rt << 1 | 1] = 0;
        col[rt] = -1;
        lsum[rt << 1] = rsum[rt << 1] = msum[rt << 1] = len - (len >> 1);
        lsum[rt << 1|1] = rsum[rt << 1|1] = msum[rt << 1|1] = len >> 1;
    }
}

void update(int L, int R, int c, int l, int r, int rt) {
    if (L <= l && R >= r) {
        col[rt] = c;
        if (c == 1)
            lsum[rt] = rsum[rt] = msum[rt] = 0;
        else
            lsum[rt] = rsum[rt] = msum[rt] = r - l + 1;
        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 c, int l, int r, int rt) {
    if (l == r)
        return l;
    pushdown(rt, r - l + 1);
    int m = (l + r) >> 1;
    if (msum[rt << 1] >= c)
        return query(c, lson);
    else if (rsum[rt << 1] + lsum[rt << 1 | 1] >= c)
        return m - rsum[rt << 1] + 1;
    else if (msum[rt << 1 | 1] >= c)
        return query(c, rson);
}

int main() {
    int n, m, op, a, b, pos;
    scanf("%d%d", &n, &m);
    memset(col,0,sizeof(col));
    build(1, n, 1);
    while (m--) {
        scanf("%d%d", &op, &a);
        if (op == 1) {
            if (msum[1] < a) {
                printf("0\n");
            } else {
                pos = query(a, 1, n, 1);
                printf("%d\n", pos);
                update(pos, pos + a - 1, 1, 1, n, 1);
            }
        } else if (op == 2) {
            scanf("%d", &b);
            update(a, a + b - 1, 0, 1, n, 1);
        }
    }
    return 0;
}