Ultraviolet A 11983-weird advertisement (line segment tree)

Link: Ultraviolet A 11983-weird Advertisement

Given n rectangles, I would like to ask how many areas are covered more than K times.

Solution: divide each rectangle into two line segments, one for adding overwrite value 1, the other for reducing overwrite value 1, and record the height (abscissa) of the two segments at the same time ). Create a line segment tree for discretization of the ordinate coordinates, and sort the line segments by height. Maintain the length of the whole range with coverage greater than K and multiply the range above the height.

#include <cstdio>#include <cstring>#include <vector>#include <algorithm>using namespace std;const int maxn = 30005;#define lson(x) ((x)<<1)#define rson(x) (((x)<<1)+1)typedef long long ll;int N, K, R;vector<int> bins, arr;struct Segment {    int l, r, h, v;    void set (int l, int r, int h, int v) {        this->l = l;        this->r = r;        this->h = h;        this->v = v;    }}seg[maxn*2];struct Node {    int l, r, add;    int c[12];    void set (int l, int r, int add) {        this->l = l;        this->r = r;        this->add = add;        memset(c, 0, sizeof(c));    }}node[maxn*24];inline bool cmp (const Segment& a, const Segment& b) {    return a.h < b.h;}inline int search (int v) {    return lower_bound(bins.begin(), bins.end(), v) - bins.begin();}void pushup (int u) {    memset(node[u].c, 0, sizeof(node[u].c));    if (node[u].l == node[u].r) {        int x = node[u].l;        node[u].c[min(K, node[u].add)] = bins[x+1] - bins[x];    } else {        for (int i = 0; i <= K; i++) {            int t = min(K, i + node[u].add);            node[u].c[t] += node[lson(u)].c[i] + node[rson(u)].c[i];        }    }}void build_segTree (int u, int l, int r) {    node[u].set(l, r, 0);     if (l == r) {        pushup(u);        return;    }    int mid = (l + r) / 2;    build_segTree(lson(u), l, mid);    build_segTree(rson(u), mid + 1, r);    pushup(u);}void insert_segTree (int u, int l, int r, int v) {    if (l <= node[u].l && node[u].r <= r) {        node[u].add += v;        pushup(u);        return;    }    int mid = (node[u].l + node[u].r) / 2;    if (l <= mid)        insert_segTree(lson(u), l, r, v);    if (r > mid)        insert_segTree(rson(u), l, r, v);    pushup(u);}int query_segTree (int u, int l, int r) {    if (l <= node[u].l && node[u].r <= r)        return node[u].c[K];    int mid = (node[u].l + node[u].r) / 2;    int ret = 0;    if (l <= mid)        ret += query_segTree(lson(u), l, r);    if (r > mid)        ret += query_segTree(rson(u), l, r);    return ret;}void add_hash (int x) {    if (x)        arr.push_back(x-1);    arr.push_back(x);    arr.push_back(x+1);}void init () {    int x1, y1, x2, y2;    arr.clear();    scanf("%d%d", &N, &K);    for (int i = 0; i < N; i++) {        scanf("%d%d%d%d", &x1, &y1, &x2, &y2);        seg[lson(i)].set(x1, x2, y1, 1);        seg[rson(i)].set(x1, x2, y2+1, -1);        add_hash(x1);        add_hash(x2);    }    sort(arr.begin(), arr.end());    bins.clear();    bins.push_back(arr[0]);    for (int i = 1; i < arr.size(); i++) {        if (arr[i] != arr[i-1])            bins.push_back(arr[i]);    }    R = bins.size() - 2;    build_segTree (1, 0, R);}ll solve () {    sort(seg, seg + 2 * N, cmp);    ll ret = 0;    for (int i = 0; i < 2 * N - 1; i++) {        insert_segTree(1, search(seg[i].l), search(seg[i].r), seg[i].v);        ll tmp = query_segTree(1, 0, R);        ret += tmp * (seg[i+1].h - seg[i].h);    }    return ret;}int main () {    int cas;    scanf("%d", &cas);    for (int kcas = 1; kcas <= cas; kcas++) {        init();        printf("Case %d: %lld\n", kcas, solve());    }    return 0;}

Ultraviolet A 11983-weird advertisement (line segment tree)