前些天看到了有人发布有关算法的贴子，说来惭愧，本人几乎忘记了如何做回溯了，花了很长时间，不段在草稿纸上模拟，上天不负有心人，最终还是做出了以前做过的几个经典案例，与大家分享一下。
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- C# code
/// <summary> /// 获取数列 /// </summary> protected void getNumList() { int[] ary = new int[] { 0, 1, 2, 2 }; ary.CopyTo(ary, 0); int s = 3; string num = "1234"; char[] ary_num = num.ToCharArray(); int n = ary_num.Length - 1; int cout = 0; string txt = string.Empty; while (s >= 0) { loop: if (ary[s] >= n) { ary[s] = -1; s = s - 1; } else { ary[s] = ary[s] + 1; for (int i = s - 1; i >= 0; i--) { if (ary[s] == ary[i]) { goto loop; } } if (s == 3 && !txt.Contains(string.Format("{0}{1}{2}{3}", ary_num[ary[0]], ary_num[ary[1]], ary_num[ary[2]], ary_num[ary[3]]))) { cout++; txt = txt + "," + string.Format("{0}{1}{2}{3}", ary_num[ary[0]], ary_num[ary[1]], ary_num[ary[2]], ary_num[ary[3]]); Response.Write(string.Format("{0}{1}{2}{3}<br/>", ary_num[ary[0]], ary_num[ary[1]], ary_num[ary[2]], ary_num[ary[3]])); } if (s < 3) { s = s + 1; } } } Response.Write(string.Format("{1}总数为：{0} 个数列", cout, num)); }- C# code
/// <summary> /// 走迷宫 /// </summary> protected void findPath() { //初使化地图 int[,] ary_map = new int[8, 12] { { 0, 0, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1 }, { 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 1, 1 }, { 1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 1, 1 }, { 0, 0, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1 }, { 0, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1 }, { 0, 0, 0, 0, 1, 0, 1, 1, 1, 1, 0, 0 }, { 1, 0, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1 }, { 0, 0, 0, 1, 1, 0, 1, 0, 0, 0, 0, 0 } }; for (int i = 0; i < 8; i++) { for (int j = 0; j < 12; j++) { Response.Write(ary_map[i, j]); } Response.Write("<br/>"); } //开始询址 int s = 0;//记录第几步 int[] st = new int[8 * 12];//记录每步的方向y - 1(上),x + 1(左),y - 1(下),x - 1(右) int x = 0;//第几步的x int y = 0;//第几步的y while (s >= 0) { //判断方向 switch (st[s]) { case 0: y = y - 1;//向上走 break; case 1: x = x + 1;//向左走 break; case 2: y = y + 1;//向下走 break; case 3: x = x - 1;//向右走 break; } //如果碰壁就往回走 if (st[s] > 4 || x < 0 || y < 0 || x >= 12 || y >= 8 || ary_map[y, x] == 1 || ary_map[y, x] == -1) { Loop://判断方向，回退到上一步 switch (st[s]) { case 0: y = y + 1; break; case 1: x = x - 1; break; case 2: y = y - 1; break; case 3: x = x + 1; break; } //换一个方向 st[s] = st[s] + 1; //所有方向都走不通就返回上一步 if (st[s] > 3) { st[s] = 0; s = s - 1; if (s > 0) goto Loop; } } else { //将走过的路径设为-1 ary_map[y, x] = -1; //下一步 s = s + 1; if (x == 11 && y == 7) { break; } } } //询址结束 //输出路径 x = 0; y = 0; string txt=string.Empty; for (int i = 0; i < s; i++) { switch (st[i]) { case 0: y = y - 1; break; case 1: x = x + 1; break; case 2: y = y + 1; break; case 3: x = x - 1; break; } if (st[i] <= 0) { break; } else { txt = (txt == "" ? "" : txt + ",") + string.Format("(x:{0},y:{1})", x, y); } } Response.Write(string.Format("<p>路径为:(x:0,y:0),{0}</p>", txt)); }