【题目链接】
【算法】
线段树
对于一个节点，记录它从左端点延伸的最多的空房间的个数，从右端点延伸的最多的空房间个数，和该区间最多的连续
空房间个数
【代码】
#include<bits/stdc++.h> using namespace std; #define MAXN 50010 int n,m,opt,pos,x,d; struct SegmentTree { struct Node { int l,r,lm,rm,mx,tag; } Tree[MAXN*4]; inline void build(int index,int l,int r) { int mid; Tree[index].l = l; Tree[index].r = r; Tree[index].lm = Tree[index].rm = Tree[index].mx = r - l + 1; Tree[index].tag = -1; if (l == r) return; mid = (l + r) >> 1; build(index<<1,l,mid); build(index<<1|1,mid+1,r); } inline void pushdown(int index) { int ql = Tree[index].l,qr = Tree[index].r; int mid = (ql + qr) >> 1; if (ql == qr) return; if (Tree[index].tag == 0) { Tree[index<<1].lm = Tree[index<<1].rm = Tree[index<<1].mx = mid - ql + 1; Tree[index<<1|1].lm = Tree[index<<1|1].rm = Tree[index<<1|1].mx = qr - mid; Tree[index<<1].tag = Tree[index<<1|1].tag = 0; Tree[index].tag = -1; } if (Tree[index].tag == 1) { Tree[index<<1].lm = Tree[index<<1].rm = Tree[index<<1].mx = 0; Tree[index<<1|1].lm = Tree[index<<1|1].rm = Tree[index<<1|1].mx = 0; Tree[index<<1].tag = Tree[index<<1|1].tag = 1; Tree[index].tag = -1; } } inline void update(int index) { int ql = Tree[index].l,qr = Tree[index].r; int mid = (ql + qr) >> 1; if (Tree[index<<1].lm == mid - ql + 1) Tree[index].lm = Tree[index<<1].lm + Tree[index<<1|1].lm; else Tree[index].lm = Tree[index<<1].lm; if (Tree[index<<1|1].rm == qr - mid) Tree[index].rm = Tree[index<<1|1].rm + Tree[index<<1].rm; else Tree[index].rm = Tree[index<<1|1].rm; Tree[index].mx = max(max(Tree[index<<1].mx,Tree[index<<1|1].mx),Tree[index<<1].rm+Tree[index<<1|1].lm); } inline void modify(int index,int l,int r,int val) { int mid,ql,qr; if (Tree[index].l == l && Tree[index].r == r) { Tree[index].lm = Tree[index].rm = Tree[index].mx = (val ^ 1) * (r - l + 1); Tree[index].tag = val; } else { pushdown(index); ql = Tree[index].l; qr = Tree[index].r; mid = (ql + qr) >> 1; if (mid >= r) modify(index<<1,l,r,val); else if (mid + 1 <= l) modify(index<<1|1,l,r,val); else { modify(index<<1,l,mid,val); modify(index<<1|1,mid+1,r,val); } update(index); } } inline int query_pos(int index,int d) { int mid,ql,qr; ql = Tree[index].l; qr = Tree[index].r; mid = (ql + qr) >> 1; if (ql == qr) return ql; pushdown(index); if (Tree[index<<1].mx >= d) return query_pos(index<<1,d); else if (Tree[index<<1].rm + Tree[index<<1|1].lm >= d) return mid - Tree[index<<1].rm + 1; else return query_pos(index<<1|1,d); } inline int query() { return Tree[1].mx; } } T; template <typename T> inline void read(T &x) { int f = 1; x = 0; char c = getchar(); for (; !isdigit(c); c = getchar()) { if (c == '-') f = -f; } for (; isdigit(c); c = getchar()) x = (x << 3) + (x << 1) + c - '0'; x *= f; } template <typename T> inline void write(T x) { if (x < 0) { putchar('-'); x = -x; } if (x > 9) write(x/10); putchar(x%10+'0'); } template <typename T> inline void writeln(T x) { write(x); puts(""); } int main() { read(n); read(m); T.build(1,1,n); while (m--) { read(opt); if (opt == 1) { read(d); if (T.query() < d) writeln(0); else { pos = T.query_pos(1,d); writeln(pos); T.modify(1,pos,pos+d-1,1); } } else { read(x); read(d); T.modify(1,x,x+d-1,0); } } return 0; }