diff --git a/src/main/java/cn/whaifree/redo/redo_all_240721/LeetCode406.java b/src/main/java/cn/whaifree/redo/redo_all_240721/LeetCode406.java
new file mode 100644
index 0000000..3a25cf8
--- /dev/null
+++ b/src/main/java/cn/whaifree/redo/redo_all_240721/LeetCode406.java
@@ -0,0 +1,54 @@
+package cn.whaifree.redo.redo_all_240721;
+
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+/**
+ * @version 1.0
+ * @Author whai文海
+ * @Date 2024/8/7 21:23
+ * @注释
+ */
+public class LeetCode406 {
+
+    @Test
+    public void test()
+    {
+        int[][] people = {{7,0},{4,4},{7,1},{5,0},{6,1},{5,2}};
+        for (int[] ints : new Solution().reconstructQueue(people)) {
+            System.out.println(Arrays.toString(ints));
+        }
+    }
+
+
+    class Solution {
+        /**
+         * [[7,0],[4,4],[7,1],[5,0],[6,1],[5,2]]
+         * @param people
+         * @return
+         */
+        public int[][] reconstructQueue(int[][] people) {
+            List<int[]> list = new ArrayList<>();
+            Arrays.sort(people, (o1, o2) -> {
+                if (o1[0] == o2[0]) {
+                    return o1[1] - o2[1];
+                } else {
+                    return o2[0] - o1[0];
+                }
+            });
+
+            /**
+             * 遍历每一个，如果身高
+             */
+            for (int i = 0; i < people.length; i++) {
+                list.add(people[i][1], people[i]);
+            }
+
+            return list.toArray(new int[people.length][2]);
+        }
+
+    }
+}
diff --git a/src/main/java/cn/whaifree/redo/redo_all_240721/LeetCode435.java b/src/main/java/cn/whaifree/redo/redo_all_240721/LeetCode435.java
new file mode 100644
index 0000000..128cdc5
--- /dev/null
+++ b/src/main/java/cn/whaifree/redo/redo_all_240721/LeetCode435.java
@@ -0,0 +1,122 @@
+package cn.whaifree.redo.redo_all_240721;
+
+import org.junit.Test;
+
+import java.util.Arrays;
+import java.util.Comparator;
+
+/**
+ * @version 1.0
+ * @Author whai文海
+ * @Date 2024/8/7 21:41
+ * @注释
+ */
+public class LeetCode435 {
+
+    @Test
+    public void test()
+    {
+        So3 solution = new So3();
+        // [0,2],[1,3],[2,4],[3,5],[4,6]
+        System.out.println(solution.eraseOverlapIntervals(new int[][]{{0, 2}, {1, 3}, {2, 4}, {3, 5}, {4, 6}}));
+        System.out.println(solution.eraseOverlapIntervals(new int[][]{{1, 2}, {1, 2}, {1, 2}}));
+        System.out.println(solution.eraseOverlapIntervals(new int[][]{{1, 2}, {2, 3}}));
+    }
+
+    class Solution {
+        public int eraseOverlapIntervals(int[][] intervals) {
+            Arrays.sort(intervals, new Comparator<int[]>() {
+                @Override
+                public int compare(int[] o1, int[] o2) {
+                    if (o1[0] == o2[0]) {
+                        return o1[1] - o2[1];
+                    }
+                    return o1[0] - o2[0];
+                }
+            });
+
+//            int start = intervals[0][0];
+            int end = intervals[0][1];
+            int res = 0;
+            for (int i = 1; i < intervals.length; i++) {
+                int[] next = intervals[i];
+                /**
+                 *  |    |
+                 *    | |
+                 *
+                 *  |    |
+                 *     |    |
+                 *
+                 *  |    |
+                 *         |    |
+                 *
+                 */
+                int nextStart = next[0];
+                int nextEnd = next[1];
+                if (end <= nextStart) {
+//                    start = nextStart;
+                    end = nextEnd;
+                }else if (nextEnd <= end) {
+                    res++;
+                    end = nextEnd;
+                } else {
+                    res++;
+                }
+            }
+            return res;
+        }
+    }
+
+    class Solution2 {
+        public int eraseOverlapIntervals(int[][] intervals) {
+            Arrays.sort(intervals, new Comparator<int[]>() {
+                @Override
+                public int compare(int[] o1, int[] o2) {
+                    return o1[1] - o2[1];
+                }
+            });
+            int end = intervals[0][1];
+            int can = 1;
+            for (int i = 1; i < intervals.length; i++) {
+                int[] next = intervals[i];
+                int nextStart = next[0];
+                int nextEnd = next[1];
+                // 如果上次活动结束比下次开始时间早，能够多参加一次
+                if (nextStart >= end) {
+                    can++;
+                    end = nextEnd;
+                }
+            }
+
+            return intervals.length - can;
+
+        }
+    }
+
+    class So3{
+        public int eraseOverlapIntervals(int[][] intervals) {
+            // 最多能参加几次活动
+            Arrays.sort(intervals, new Comparator<int[]>() {
+                @Override
+                public int compare(int[] o1, int[] o2) {
+                    return o1[0] - o2[0];
+                }
+            });
+
+            int participation = 1;
+            int end = intervals[0][1];
+            for (int i = 1; i < intervals.length; i++) {
+                if (intervals[i][0] < end) {
+                    // 后一个活动的开始时间早于头一个活动开始时间，这个活动不能参加
+                    end = Math.min(end, intervals[i][1]);
+                } else {
+                    participation++;
+                    end = intervals[i][1];
+                }
+            }
+
+            return intervals.length - participation;
+
+        }
+    }
+}