西安葡萄城校招一面面试题（挺有意思）
作者：互联网
前几天参加西安葡萄城的校招面试，发挥挺拉跨的，但没想到一面还是过了，当时面试官问了我一个面试题，感觉挺有意思的，在这记录一下，并手动实现。
问题：
给n个窗口的打开顺序，然后每个窗口的左上角顶点的坐标，和宽高，还有一个光标的坐标。问光标所在位置是哪个窗口，并且这个窗口的可视面积?（窗口与窗口之间重叠后，后打开的窗口会把先打开的窗口覆盖）
问题一找到光标在哪一个窗口？
思路：
根据给定的打开顺序，从后向前遍历，光标是否在当前窗口。
第二个问题求某个窗口的可视面积？
对某个窗口中的数据处理成矩形，用扫描线来做
代码：
//makefile
src = $(wildcard ./*.cpp)
obj = $(patsubst %.cpp, %.o, $(src))
target = app
CC = g++
$(target): $(obj)
$(CC) $(obj) -o $(target)
%.o: %.cpp
$(CC) -c $< -o $@
.PHONY: clean
clean:
rm -rf $(obj) $(target)
#include <algorithm>
#include <iostream>
#include <memory>
#include <unordered_map>
#include <vector>
#ifndef _VIEWARE_H_
#define _VIEWARE_H_
#define L INT_MIN
#define R INT_MAX
class Windows;
class Line;
class GetFillArea;
class Soultion;
class Windows {
public:
Windows() {}
Windows(int windowsNums)
: _windowsSize(windowsNums), _worldHeight(100), _worldWidth(100) {
_worldIndex.first = _worldIndex.second = 0;
}
~Windows() {}
int _windowsSize;
int _worldHeight;
int _worldWidth;
static std::vector<int> _coordinate;
std::pair<int, int> _worldIndex; //世界坐标原点
std::vector<std::vector<int>> _worldCoordinate; //世界坐标点
void setWindowsSize(int size) { this->_windowsSize = size; }
void setWorldHeight(int heigth) { this->_worldHeight = heigth; }
void setWorldWidth(int width) { this->_worldWidth = width; }
void insertCoordinate(int x, int y, int width, int height);
int findWindows(int x, int y);
void buildPartialData(int windowsIndex); //构造局部矩形内的数据
void prPartia();
std::vector<std::vector<int>> _partiaMatrix;
};
class Line {
public:
Line(int sx, int sty, int sdy, bool sfla)
: x(sx), ty(sty), dy(sdy), fla(sfla) {}
int x, ty, dy;
bool fla;
bool operator<(const Line& a) { return x < a.x; }
};
class GetFillArea {
public:
GetFillArea() {}
std::unordered_map<int, int> Len, Lazy, Rson, Lson;
std::vector<Line> line;
std::vector<int> _axis;
void prepareData(std::vector<std::vector<int>>& matrix);
void buildTree(int k, int Ls, int Rs);
void updateInterval(int k, int l, int r, int w);
void pushUp(int k);
int getFillArea();
bool isfill = false;
};
class Soultion {
public:
Soultion(){};
int getViewArea(std::vector<std::vector<int>>& Matrix,int x,int y);
};
#endif
#include "Viewarea.h"
std::vector<int> Windows::_coordinate(4, 0);
void Windows::insertCoordinate(int x, int y, int width, int height) {
this->_coordinate[0] = x;
this->_coordinate[1] = y;
this->_coordinate[2] = x + width;
this->_coordinate[3] = y + height;
this->_worldCoordinate.push_back(_coordinate);
}
int Windows::findWindows(int x, int y) {
int Index = -1;
for (int i = this->_worldCoordinate.size() - 1; i >= 0; i--) {
if (x >= _worldCoordinate[i][0] && y >= _worldCoordinate[i][1] &&
x <= _worldCoordinate[i][2] && y <= _worldCoordinate[i][3]) {
return i;
}
}
return Index;
}
void Windows::buildPartialData(int windowsindex) {
int _ax = this->_worldCoordinate[windowsindex][0];
int _ay = this->_worldCoordinate[windowsindex][1];
int _dx = this->_worldCoordinate[windowsindex][2];
int _dy = this->_worldCoordinate[windowsindex][3];
int _bx = _dx;
int _by = _ay;
int _cx = _ax;
int _cy = _dy;
for (int i = windowsindex + 1; i < this->_worldCoordinate.size(); i++) {
int ax = this->_worldCoordinate[i][0];
int ay = this->_worldCoordinate[i][1];
int dx = this->_worldCoordinate[i][2];
int dy = this->_worldCoordinate[i][3];
int bx = dx;
int by = ay;
int cx = ax;
int cy = dy;
bool isA, isB, isC, isD;
int vertex = 0;
isA = isB = isC = isD = false;
if (ax >= _ax && ay >= _ay && ax <= _dx && ay <= _dy) {
isA = true;
vertex++;
}
if (bx >= _ax && by >= _ay && bx <= _dx && by <= _dy) {
isB = true;
vertex++;
}
if (cx >= _ax && cy >= _ay && cx <= _dx && cy <= _dy) {
isC = true;
vertex++;
}
if (dx >= _ax && dy >= _ay && dx <= _dx && dy <= _dy) {
isD = true;
vertex++;
}
if (!vertex) {
continue;
} else if (vertex == 1) {
if (isA) {
this->_coordinate[0] = ax;
this->_coordinate[1] = ay;
this->_coordinate[2] = _dx;
this->_coordinate[3] = _dy;
} else if (isB) {
this->_coordinate[0] = _cx;
this->_coordinate[1] = by;
this->_coordinate[2] = bx;
this->_coordinate[3] = _cy;
} else if (isC) {
this->_coordinate[0] = cx;
this->_coordinate[1] = _by;
this->_coordinate[2] = _bx;
this->_coordinate[3] = cy;
} else if (isD) {
this->_coordinate[0] = _ax;
this->_coordinate[1] = _ay;
this->_coordinate[2] = dx;
this->_coordinate[3] = dy;
}
this->_partiaMatrix.push_back(this->_coordinate);
} else if (vertex == 2) {
if (isA && isB) {
this->_coordinate[0] = ax;
this->_coordinate[1] = ay;
this->_coordinate[2] = bx;
this->_coordinate[3] = std::min(dy, _dy);
} else if (isC && isD) {
this->_coordinate[0] = cx;
this->_coordinate[1] = std::max(ay, _ay);
this->_coordinate[2] = dx;
this->_coordinate[3] = dy;
} else if (isA && isC) {
this->_coordinate[0] = ax;
this->_coordinate[1] = ay;
this->_coordinate[2] = std::min(dx, _dx);
this->_coordinate[3] = cy;
} else if (isB && isD) {
this->_coordinate[0] = std::max(ax, _ax);
this->_coordinate[1] = ay;
this->_coordinate[2] = dx;
this->_coordinate[3] = dy;
} else {
this->_coordinate[0] = ax;
this->_coordinate[1] = ay;
this->_coordinate[2] = dx;
this->_coordinate[3] = dy;
}
this->_partiaMatrix.push_back(this->_coordinate);
} else {
this->_coordinate[0] = ax;
this->_coordinate[1] = ay;
this->_coordinate[2] = dx;
this->_coordinate[3] = dy;
this->_partiaMatrix.push_back(this->_coordinate);
}
}
}
void Windows::prPartia() {
for (auto x : this->_partiaMatrix) {
std::cout << x[0] << ' ' << x[1] << ' ' << x[2] << ' ' << x[3] << std::endl;
}
}
void GetFillArea::prepareData(std::vector<std::vector<int>>& matrix) {
for (auto& Matrix : matrix) {
Line lf(Matrix[0], Matrix[1], Matrix[3], true);
Line ls(Matrix[2], Matrix[1], Matrix[3], false);
this->line.push_back(lf);
this->line.push_back(ls);
this->_axis.push_back(Matrix[1]);
this->_axis.push_back(Matrix[3]);
}
if (matrix.empty()) {
isfill = true;
return;
}
sort(line.begin(), line.end());
sort(_axis.begin(), _axis.end());
}
void GetFillArea::pushUp(int k) {
if (Lazy[k]) {
Len[k] = Rson[k] - Lson[k];
} else {
Len[k] = Len[k << 1] + Len[k << 1 | 1];
}
}
void GetFillArea::buildTree(int k, int Ls, int Rs) {
Lson[k] = _axis[Ls - 1], Rson[k] = _axis[Rs - 1];
if (Rs - Ls <= 1) {
return;
}
int MID = (Ls + Rs) >> 1;
buildTree(k << 1, Ls, MID);
buildTree(k << 1 | 1, MID, Rs);
}
void GetFillArea::updateInterval(int k, int l, int r, int w) {
if (Lson[k] >= l && Rson[k] <= r) {
Lazy[k] += w;
pushUp(k);
return;
}
if (Rson[k << 1] > l) {
updateInterval(k << 1, l, r, w);
}
if (Lson[k << 1 | 1] < r) {
updateInterval(k << 1 | 1, l, r, w);
}
pushUp(k);
}
int GetFillArea::getFillArea() {
int fillareas = 0;
if (isfill) {
return fillareas;
}
buildTree(1, 1, _axis.size());
for (int i = 0; i < this->line.size() - 1; i++) {
int pw = line[i].fla ? 1 : -1;
updateInterval(1, line[i].ty, line[i].dy, pw);
fillareas += Len[1] * (line[i + 1].x - line[i].x);
}
return fillareas;
}
int Soultion::getViewArea(std::vector<std::vector<int>>& Matrix, int x, int y) {
std::shared_ptr<Windows> windows = std::make_shared<Windows>(Matrix.size());
std::shared_ptr<GetFillArea> getfill = std::make_shared<GetFillArea>();
for (auto pos : Matrix) {
windows->insertCoordinate(pos[0], pos[1], pos[2], pos[3]);
}
int _index = windows->findWindows(x, y);
int allAreas = abs(windows->_worldCoordinate[_index][0] -
windows->_worldCoordinate[_index][2]) *
abs(windows->_worldCoordinate[_index][1] -
windows->_worldCoordinate[_index][3]);
windows->buildPartialData(_index);
getfill->prepareData(windows->_partiaMatrix);
return allAreas - getfill->getFillArea();
}
#include <iostream>
#include <memory>
#include "Viewarea.h"
int main() {
std::shared_ptr<Soultion> soultion = std::make_shared<Soultion>();
/*测试数据*/
std::vector<std::vector<int>> Matrix = {{1, 1, 3, 3}, {1, 1, 1, 1},
{1, 3, 1, 2}, {3, 2, 2, 2},
{4, 4, 2, 2}, {2, 2, 5, 5}};
/*光标所在位置*/
int gx, gy;
gx = 4, gy = 1;
std::cout << "ViewArea: " << soultion->getViewArea(Matrix, gx, gy) << std::endl;
return 0;
}
标签：std,worldCoordinate,面试题,int,城校,有意思,ay,coordinate,ax 来源： https://blog.csdn.net/yangzijiangac/article/details/120514056