diff --git a/src/main/java/contest/y2021/jx.java b/src/main/java/contest/y2021/jx.java
new file mode 100644
index 0000000..c6bc48c
--- /dev/null
+++ b/src/main/java/contest/y2021/jx.java
@@ -0,0 +1,119 @@
+package contest.y2021;
+
+import com.code.leet.entiy.ListNode;
+import com.code.leet.entiy.TwoArray;
+
+import java.util.*;
+
+/**
+ * @description:
+ * @author: Administrator
+ * @date: 2021/10/29-19:00
+ */
+public class jx {
+
+    public ListNode deleteListNode(ListNode head) {
+        ListNode temp = head;
+        while (temp != null && temp.next != null) {
+            temp.next = temp.next.next;
+            temp = temp.next;
+        }
+        return head;
+    }
+
+    public int[] analysisHistogram(int[] heights, int cnt) {
+        Arrays.sort(heights);
+        int min = heights[heights.length - 1];
+        int index = 0;
+        for (int i = 0; i <= heights.length - cnt; i++) {
+            int sub = heights[i + cnt - 1] - heights[i];
+            if (sub < min) {
+                min = sub;
+                index = i;
+            }
+        }
+        return Arrays.copyOfRange(heights, index, index + cnt - 1);
+    }
+
+    public int[] metroRouteDesignI(int[][] lines, int start, int end) {
+        Map<Integer, List<Integer>> nextMap = new HashMap<>();
+        Map<Integer, List<Integer>> inMap = new HashMap<>();
+        for (int i = 0; i < lines.length; i++) {
+            int[] line = lines[i];
+            for (int j = 0; j < line.length; j++) {
+                List<Integer> list = inMap.getOrDefault(line[j], new ArrayList<>());
+                list.add(i);
+                inMap.put(line[j], new ArrayList<>(list));
+                list = nextMap.getOrDefault(line[j], new ArrayList<>());
+                if (j > 0 && (!list.contains(line[j - 1]))) {
+                    list.add(line[j - 1]);
+                }
+                if (j < line.length - 1 && (!list.contains(line[j + 1]))) {
+                    list.add(line[j + 1]);
+                }
+                nextMap.put(line[j], new ArrayList<>(list));
+            }
+        }
+        Queue<int[]> queue = new LinkedList<>();
+
+        return null;
+    }
+
+    //    public int electricityExperiment(int row, int col, int[][] position) {
+//        Arrays.sort(position, Comparator.comparingInt(a -> a[1]));
+//        dfs(position, position[0][0], position[0][1], 0, row);
+//        return count;
+//    }
+//
+//    int count = 0;
+//
+//    private void dfs(int[][] position, int x, int y, int index, int row) {
+//        if (y == position[position.length - 1][1]) {
+//            if (x == position[position.length - 1][0]) {
+//                count++;
+//            }
+//        }
+//        if (index == position.length || (y == position[index][1] && x != position[index][0])) {
+//            return;
+//        }
+//        index = y == position[index][1] && x == position[index][0] ? index + 1 : index;
+//        if (x > 0) {
+//            dfs(position, x - 1, y + 1, index, row);
+//        }
+//        dfs(position, x, y + 1, index, row);
+//        if (x < row) {
+//            dfs(position, x + 1, y + 1, index, row);
+//        }
+//    }
+
+    public static void main(String[] args) {
+        jx jx = new jx();
+        TwoArray twoArray = new TwoArray("[[1,3],[3,5],[2,0]]",true);
+
+        System.out.println(jx.electricityExperiment(5,6, twoArray.getArr()));
+    }
+
+    public int electricityExperiment(int row, int col, int[][] position) {
+        Arrays.sort(position, Comparator.comparingInt(a -> a[1]));
+        int[][] arrs = new int[row][col];
+        arrs[position[0][0]][position[0][1]] = 1;
+        int index = 1;
+        for (int i = position[0][1] + 1; i <= position[position.length - 1][1]; i++) {
+            for (int j = 0; j < row; j++) {
+                if (j > 0) {
+                    arrs[j][i] += arrs[j - 1][i - 1];
+                }
+                arrs[j][i] += arrs[j][i - 1];
+                if (j < row - 1) {
+                    arrs[j][i] += arrs[j + 1][i - 1];
+                }
+            }
+        }
+        for (int[] pos : position) {
+            if (arrs[pos[0]][pos[1]] == 0) {
+                return 0;
+            }
+        }
+        return arrs[position[position.length - 1][0]][position[position.length - 1][1]];
+    }
+}