UV 1517-tracking RFIDs (STL + ry)

Link to the question: Ultraviolet A 1517-tracking RFIDs

Given S, R, W, P, indicates that there are R sensors, the sensing radius is R, W wall blocking, p products, and the location of S sensors is given, the position of W wall blocking (points at both ends) and the position of P products. The output position of each product can be determined by those sensors. If there is a wall between the sensor and the product, K is added to the distance.

Solution: the number of S is large, but the number of R is small. Therefore, enumerate the points in the distance between the coordinates of each product and add or subtract the points in the r range to determine whether a sensor exists. If the distance is satisfied, when judging the distance, you need to enumerate the wall location and determine whether the two line segments are intersecting. You can use the property of the vector cross product to determine.

#include <cstdio>#include <cstring>#include <set>#include <vector>#include <algorithm>using namespace std;typedef long long ll;struct point {    int x, y;    point (int x = 0, int y = 0) {        this->x = x;        this->y = y;    }    point operator + (const point& u) {        return point(x + u.x, y + u.y);    }    point operator - (const point& u) {        return point(x - u.x, y - u.y);    }    int operator ^ (const point& u) {        return x * u.y - y * u.x;    }    bool operator < (const point& u) const {        if (x != u.x)            return x < u.x;        return y < u.y;    }};typedef pair<point, point> line;int S, R, W, P;set<point> pset;vector<line> pline;void init () {    pset.clear();    pline.clear();    scanf("%d%d%d%d", &S, &R, &W, &P);    point u, v;    for (int i = 0; i < S; i++) {        scanf("%d%d", &u.x, &u.y);        pset.insert(u);    }    for (int i = 0; i < W; i++) {        scanf("%d%d%d%d", &u.x, &u.y, &v.x, &v.y);        pline.push_back(make_pair(u, v));    }}bool check (point a, point b, point c, point d) {    if (max(a.x, b.x) < min(c.x, d.x) ||        max(a.y, b.y) < min(c.y, d.y) ||        min(a.x, b.x) > max(c.x, d.x) ||        min(a.y, b.y) > max(c.y, d.y) )        return false;    ll i = (b - a) ^ (b - c);    ll j = (b - a) ^ (b - d);    ll p = (d - c) ^ (d - a);    ll q = (d - c) ^ (d - b);    return i * j <= 0 && p * q <= 0;}bool judge (point u, int x, int y) {    if (x * x + y * y > R * R)        return false;    point v = u + point(x, y);    if (!pset.count(v))        return false;    int cnt = 0;    for (int i = 0; i < W; i++) {        if (check(u, v, pline[i].first, pline[i].second))            cnt++;    }    if (cnt > R)        return false;    return x * x + y * y <= (R - cnt) * (R - cnt);}void solve () {    point u;    vector<point> ans;    for (int i = 0; i < P; i++) {        ans.clear();        scanf("%d%d", &u.x, &u.y);        for (int x = -R; x <= R; x++) {            for (int y = -R; y <= R; y++) {                if (judge(u, x, y))                    ans.push_back(u + point(x, y));            }        }        sort(ans.begin(), ans.end());        printf("%lu", ans.size());        for (int i = 0; i < ans.size(); i++)            printf(" (%d,%d)", ans[i].x, ans[i].y);        printf("\n");    }}int main () {    int cas;    scanf("%d", &cas);    while (cas--) {        init();        solve();    }    return 0;}

UV 1517-tracking RFIDs (STL + ry)