poj 3667 Hotel
http://poj.org/problem?id=3667
又是一道线段树的题,这次的操作是【区间更新,查询最大连续区间】。这题是之前一题"内存管理"的模拟题的简化版,在插入区间前先查找满足要求的位置,然后就直接整段覆盖,删除也就是简单的删除区间。注意细节就好了!
刚开始的时候打算查找和覆盖打在一起,后来发现这样的操作十分困难,所以还是将查找和覆盖分离了。所以插入区间和删除区间也变成两部分了。
代码如下:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 #include <cstdio> 2 #include <cstring> 3 #include <cstdlib> 4 #include <algorithm> 5 6 using namespace std; 7 8 #define lson l, m, rt << 1 9 #define rson m + 1, r, rt << 1 | 1 10 11 const int maxn = 50005; 12 13 struct Hotel { 14 int mx, len; 15 int l, r; 16 17 Hotel(int _len = 0, int _set = 0) { 18 mx = l = r = _set; 19 len = _len; 20 } 21 } room[maxn << 2]; 22 int late[maxn << 2]; 23 24 Hotel up(Hotel left, Hotel right) { 25 Hotel ret; 26 27 ret.len = left.len + right.len; 28 ret.mx = max(left.mx, right.mx); 29 ret.mx = max(ret.mx, left.r + right.l); 30 ret.l = left.l; 31 ret.r = right.r; 32 if (left.l == left.len) ret.l += right.l; 33 if (right.r == right.len) ret.r += left.r; 34 35 return ret; 36 } 37 38 void down(int rt) { 39 if (~late[rt]) { 40 int l = rt << 1; 41 int r = rt << 1 | 1; 42 43 late[l] = late[r] = late[rt]; 44 room[l] = Hotel(room[l].len, late[rt] * room[l].len); 45 room[r] = Hotel(room[r].len, late[rt] * room[r].len); 46 late[rt] = -1; 47 } 48 } 49 50 void build(int l, int r, int rt) { 51 late[rt] = -1; 52 if (l == r) { 53 room[rt] = Hotel(1, 1); 54 //printf("%d %d : %d %d %d %d\n", l, r, room[rt].mx, room[rt].len, room[rt].l, room[rt].r); 55 56 return ; 57 } 58 int m = (l + r) >> 1; 59 60 build(lson); 61 build(rson); 62 room[rt] = up(room[rt << 1], room[rt << 1 | 1]); 63 //printf("%d %d : %d %d %d %d\n", l, r, room[rt].mx, room[rt].len, room[rt].l, room[rt].r); 64 } 65 66 int find(int len, int l, int r, int rt){ 67 if (room[rt].mx < len) return 0; 68 if (room[rt].len == room[rt].mx) return l; 69 70 int m = (l + r) >> 1; 71 72 if (room[rt << 1].mx >= len) return find(len, lson); 73 if (room[rt << 1].r + room[rt << 1 | 1].l >= len) return m - room[rt << 1].r + 1; 74 return find(len, rson); 75 } 76 77 void add(int L, int R, int l, int r, int rt) { 78 if (L <= l && r <= R){ 79 late[rt] = 0; 80 room[rt] = Hotel(room[rt].len); 81 //printf("%d %d : %d %d %d %d\n", l, r, room[rt].mx, room[rt].len, room[rt].l, room[rt].r); 82 83 return ; 84 } 85 int m = (l + r) >> 1; 86 87 down(rt); 88 if (L <= m) add(L, R, lson); 89 if (m < R) add(L, R, rson); 90 room[rt] = up(room[rt << 1], room[rt << 1 | 1]); 91 //printf("%d %d : %d %d %d %d\n", l, r, room[rt].mx, room[rt].len, room[rt].l, room[rt].r); 92 } 93 94 void sub(int L, int R, int l, int r, int rt) { 95 if (L <= l && r <= R) { 96 late[rt] = 1; 97 room[rt] = Hotel(room[rt].len, room[rt].len); 98 //printf("%d %d : %d %d %d %d\n", l, r, room[rt].mx, room[rt].len, room[rt].l, room[rt].r); 99 100 return ; 101 } 102 int m = (l + r) >> 1; 103 104 down(rt); 105 if (L <= m) sub(L, R, lson); 106 if (m < R) sub(L, R, rson); 107 room[rt] = up(room[rt << 1], room[rt << 1 | 1]); 108 //printf("%d %d : %d %d %d %d\n", l, r, room[rt].mx, room[rt].len, room[rt].l, room[rt].r); 109 } 110 111 void deal(int n, int m) { 112 build(1, n, 1); 113 while (m--) { 114 int op; 115 int x, y; 116 117 scanf("%d", &op); 118 if (op == 1) { 119 scanf("%d", &x); 120 121 int pos = find(x, 1, n, 1); 122 123 printf("%d\n", pos); 124 if (pos) add(pos, pos + x - 1, 1, n, 1); 125 } else { 126 scanf("%d%d", &x, &y); 127 sub(x, x + y - 1, 1, n, 1); 128 } 129 } 130 } 131 132 int main() { 133 int n, m; 134 135 //freopen("in", "r", stdin); 136 while (~scanf("%d%d", &n, &m)) { 137 deal(n, m); 138 } 139 140 return 0; 141 }
——written by Lyon