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[leetcode-593-Valid Square]

osi poi 相等 code int art tab gre span

Given the coordinates of four points in 2D space, return whether the four points could construct a square.
The coordinate (x,y) of a point is represented by an integer array with two integers.
Example:
Input: p1 = [0,0], p2 = [1,1], p3 = [1,0], p4 = [0,1]
Output: True
Note:
All the input integers are in the range [-10000, 10000].
A valid square has four equal sides with positive length and four equal angles (90-degree angles).
Input points have no order.

思路:

4個點,求出任意兩點之間的距離,總共6條線段,存在其中4條相等,而且另外兩條也相等就是正方形。

double length(vector<int>& p1, vector<int>& p2)
{  
  int x = abs(p1[0] - p2[0]);
  int y = abs(p1[1] - p2[1]);
  return x*x + y*y;
}
 bool validSquare(vector<int>& p1, vector<int>& p2, vector<int>& p3, vector<int
>& p4) { map<double,int>table; table[length(p1,p2)]++; table[length(p1,p3)]++; table[length(p1,p4)]++; table[length(p2,p3)]++; table[length(p2,p4)]++; table[length(p3,p4)]++; if(table.size()!=2) return false; map<double ,int>::iterator it = table.begin(); map
<double ,int>::iterator temp = it; temp++; if((it->second ==4 && temp->second ==2 ) ||(it->second ==2 && temp->second ==4) )return true; return false; }

參考:

http://blog.csdn.net/yuer158462008/article/details/47374545

[leetcode-593-Valid Square]