标签：des style blog http color io os ar for
7.4 Write methods to implement the multiply, subtract, and divide operations for integers. Use only the add operator.
比较简单。但是要封装得好。
7.5 Given two squares on a two-dimensional plane, find a line that would cut these two squares in half. Assume that the top and the bottom sides of the square run parallel to the x-axis.
怎样写得简洁。要解决：
1. 怎么把多种情况综全考虑？
这类题就是先把special case想法，再写算法。
7.6 Given a two-dimensional graph with points on it, find a line which passes the most number of points.
见此。当时没考虑精度的问题。
1 int findMaxLine(vector<int> &points) { 2 int max = 0; 3 int dup = 0; 4 map<int, int> counts; 5 double epison = 0.0001; 6 7 for (int i = 0; i < points.size(); ++i) { 8 counts.clear(); 9 dup = 1; 10 int m = 0; 11 for (int j = i + 1; j < points.size(); ++j) { 12 if (points[i].x == points[j].x && points[i].y == points[j].y) { 13 dup++; 14 } else if (points[i].x == points[j].x) { 15 counts[0]++; 16 if (counts[0] > m) m = counts[0]; 17 } else { 18 double k = (points[i].y - points[j].y) * 1.0 / (points[i].x - points[j].x); 19 counts[(int)(k/epison)]++; 20 if (counts[int)(k/epison)] > m) m = counts[int)(k/epison)]; 21 } 22 } 23 if (m + dup > max) max = m + dup; 24 } 25 return max; 26 }
7.7 Design an algorithm to find the kth number such that the only prime factors are 3, 5, and 7.
1 int findKthMagicNumber(int k) { 2 vector<queue<int> > queues(3); 3 queues[2].push(1); 4 5 for (int i = 0; i < k; ++i) { 6 int minIndex = 0, minNumber; 7 for (int j = 1; j < 3; ++j) { 8 if (!queues[j].empty() && queues[j].front() < queues[minIndex].front()) minIndex = j; 9 } 10 minNumber = queues[minIndex].front(); 11 for (int j = minIndex; j < 3; ++j) { 12 queues[j].push(minNumber * nums[j]); 13 } 14 queues[minIndex].pop(); 15 } 16 return minNumber; 17 }
标签：des style blog http color io os ar for
原文地址：http://www.cnblogs.com/linyx/p/3910958.html
