Using the breadth-first search algorithm path

Original link: http://www.cnblogs.com/zzandliz/p/5143519.html

Description of the problem: Given a 32x32 map, the map has a number of obstacles, use the blue square to draw, design algorithm to find a path of obstacles can not touch the transfer from the upper left to the lower right corner of the map, and draw the green line .

Ideas: the first to use the full map of the BFS search, find remove obstacles to reach the minimum number of steps per a point outside of the points. And then plotted points around the current path to the minimum number of steps in turn points.

Needless to say you can tell this is a job. . . Code is very rough, with many parts of the variable represented by a specific value, just to show the effect achieved.

1. %BFS路径搜索
2. %Date-2015-12-29
3. %-----初始化-----
4. clear all;
5. clc
6. z=zeros(32,32);
7. grd=zeros(32,32);
8. grd(1,:)=1;
9. grd(32,:)=1;
10. grd(:,1)=1;
11. grd(:,32)=1;
12. grd(6:12,7:12)=1;
13. grd(20:27,4:8)=1;
15. grd(16,22:27)=1;
16. grd(10:27,18)=1;
17. grd(7:16,27)=1;
18. grd(24,12:19)=1;
21. gimag=grd;
22. grd1=grd;
23. Tempx=2;
24. Tempy=2;
25. grd(Tempx,Tempy)=2;
26. grd(31,31)=3131;
27. distancemin=64;
28. route=zeros(32,32);%32,32
29. route(2,2)=1;
30. length=5;
31. flag=0;
32. dirc=0;
34. xqueue = zeros(3131);
35. yqueue = zeros(3131);
36. xqueue(1) = 2;
37. yqueue(1) = 2;
38. startflag = 1;
39. endflag = 1;
41. while 1
42. for i=-1:1
43. for j= -1:1;
44. if grd(xqueue(startflag)+i,yqueue(startflag)+j)==0||grd(xqueue(startflag)+i,yqueue(startflag)+j)>grd(xqueue(startflag),yqueue(startflag))+1
45. grd(xqueue(startflag)+i,yqueue(startflag)+j)=grd(xqueue(startflag),yqueue(startflag))+1;
46. xqueue(endflag+1) = xqueue(startflag)+i;
47. yqueue(endflag+1) = yqueue(startflag)+j;
48. endflag = endflag+1;
50. end
51. end
52. end
53. if grd(31,31) ~= 3131
54. break;
55. end
56. startflag = startflag + 1;
57. end
59. xnow = 2;
60. ynow = 2;
61. z(2,2) = 1;
62. for i = 1:100
63. max = 0;
64. for p = 1:-1:-1
65. for q = 1:-1:-1
66. if grd(xnow+p,ynow+q)>max&&z(xnow+p,ynow+q)==0
67. max = grd(xnow+p,ynow+q);
69. xnowmax = xnow+p;
70. ynowmax = ynow+q;
71. end
72. end
73. end
74. xnow = xnowmax;
75. ynow = ynowmax;
76. route(xnowmax,ynowmax) = 1;
77. z(xnowmax,ynowmax)=1;
78. imh = image(cat(3,z,route,gimag));
79. set(imh, 'cdata', cat(3,z,route,gimag));
80. drawnow;
81. pause(0.1);
82. if xnow==31&&ynow==31
83. break;
84. end
85. end
87. %

effect:

Is known from notes (Wiz)

Reproduced in: https: //www.cnblogs.com/zzandliz/p/5143519.html