HDU 2795 Billboard (bulletin board, line segment tree application), hdu2795

HDU 2795 Billboard (bulletin board, line segment tree application), hdu2795
HDU 2795 Billboard)

ACM

Address: HDU 2795 Billboard

Question:
To post an announcement on the h * w publicity board, the height of each announcement is 1, and each announcement should be posted to the top and left as far as possible, give you the length of a series of announcements and ask if they can be pasted.

Analysis:
I don't really think about it, but I think it's easy to write.
You just need to put the billboards in the correct place. At this time, you can enter announcements in h positions. when filling out announcements, you can try to find the right position on the leftmost.
We can use a line segment tree. The search complexity is O (logn). Note that h has a very large range. If it is true, the Large Line Segment tree cannot be opened, but the range of n is only 20 w, and even if all announcements occupy a column, it will not exceed n, so the line segment tree can open min (h, n.

Code:

/**  Author:      illuz <iilluzen[at]gmail.com>*  Blog:        http://blog.csdn.net/hcbbt*  File:        2795.cpp*  Create Date: 2014-08-05 16:12:47*  Descripton:  segment tree */#include <iostream>#include <cstdio>#include <cstring>#include <algorithm>#include <map>using namespace std;#define repf(i,a,b) for(int i=(a);i<=(b);i++)#define lson(x) ((x) << 1)#define rson(x) ((x) << 1 | 1)typedef long long ll;const int N = 200010;const int ROOT = 1;int h, w, n, t;// below is sement point updated versionstruct seg {    ll w;};struct segment_tree {     seg node[N << 2];    void update(int pos) {        node[pos].w = max(node[lson(pos)].w, node[rson(pos)].w);    }    void build(int l, int r, int pos) {        if (l == r) {            node[pos].w = w;            return;        }        int m = (l + r) >> 1;        build(l, m, lson(pos));        build(m + 1, r, rson(pos));        update(pos);    }    int queryandmodify(int l, int r, int pos, ll y) {        if (y > node[pos].w) {            return -1;        }        if (l == r) {            node[pos].w -= y;            return l;        }        int m = (l + r) >> 1;        int res;        if (y <= node[lson(pos)].w)            res = queryandmodify(l, m, lson(pos), y);        else            res = queryandmodify(m + 1, r, rson(pos), y);        update(pos);        return res;    }} sgm;int main() {    while (~scanf("%d%d%d", &h, &w, &n)) {        h = min(h, n);        sgm.build(1, h, ROOT);        repf (i, 1, n) {            scanf("%d", &t);            printf("%d\n", sgm.queryandmodify(1, h, ROOT, t));        }    }    return 0;}