[Leetcode] Self Crossing

You is given an array x of n positive numbers. You start at point (0,0) and moves x[0] metres to the north, then x[1] metres to the west, x[2] metres to the south, X[3] metres to the east and so on. In the other words, after each move your direction changes counter-clockwise.

Write a one-pass algorithm with O (1) Extra space to determine, if your path crosses itself, or not.

Example 1:

Given x = [2112],┌───┐│     │└───┼──>Returntrue (self crossing)

Example 2:

Given x = [1234],┌──────┐│          │││└────────────>Returnfalse (notself crossing)

Example 3:

Given x = [1111],┌───┐│     │└───┼>Returntrue (self crossing)

Thinking of solving problems

The intersection can be divided into the following three cases:

• The fourth line intersects the first line
• Fifth line intersects or overlaps the first line
• The sixth line intersects the first line
  
  Point Xi is the last point given.

Implementation code

//Runtime:1 MS Public  class solution {     Public Boolean isselfcrossing(int[] x) {intlen = x.length;if(Len <=3)return false; for(inti =3; i < Len; i++) {if(X[i] >= x[i-2] && x[i-1] <= x[i-3]) {return true; }if(I >=4) {if(x[i-1] = = x[i-3] && X[i] + x[i-4] >= x[i-2]) {return true; }            }if(I >=5) {if(x[i-2]-x[i-4] >=0&& X[i] >= x[i-2]-x[i-4] && x[i-1] >= x[i-3]-x[i-5] && x[i-1] <= x[i-3]) {return true; }            }        }return false; }}

[Leetcode] Self Crossing