POJ - 3667 Hotel (线段树 + 区间合并)

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

1
4
7
0
5

/*
Author: 2486
Memory: 2464 KB		Time: 875 MS
Language: G++		Result: Accepted
*/
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <vector>
#include <queue>
using namespace std;
#define lson rt << 1, l, mid
#define rson rt << 1|1, mid + 1, r
#define root 1, 1, n
const int MAXN = 50000 + 5;
//(0)代表着空区间 
//msum代表着区域内的最长连续空区间， 
//lsum代表着从左端点L开始最长连续空区间， 
//rsum代表着从右端点R向前数的最长连续空区间。 
int lsum[MAXN << 2], rsum[MAXN << 2], msum[MAXN << 2];
int col[MAXN << 2];

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


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



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



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



int query(int wid, int rt, int l, int r) {
    if(l == r) return l;
    pushdown(rt, r - l + 1);
    int mid = (l + r) >> 1;
    if(msum[rt << 1] >= wid) return query(wid, lson);
    else if(rsum[rt << 1] + lsum[rt << 1|1] >= wid) return mid - rsum[rt << 1] + 1;
    return query(w,rson);
    //先在左子区间找是否有容纳长度为wid的空区间存在。 
    //如果没有，就在他们的接壤的地方找，如果还是没有找到的话，就在右子区间寻
}

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