fd

Author: dingjikerbo

solution/src/main/java/com/inuker/solution/FindAllDuplicatesInAnArray.java

@@ -13,8 +13,9 @@ public List<Integer> findDuplicates(int[] nums) {
         List<Integer> res = new ArrayList<>();
         for (int i = 0; i < nums.length; ++i) {
             int index = Math.abs(nums[i]) - 1;
-            if (nums[index] < 0)
+            if (nums[index] < 0) {
                 res.add(Math.abs(index + 1));
+            }
             nums[index] = -nums[index];
         }
         return res;

solution/src/main/java/com/inuker/solution/FindAllNumbersDisappearedInAnArray.java

@@ -8,20 +8,26 @@
  */
 
 public class FindAllNumbersDisappearedInAnArray {
+    //4,3,2,7,8,2,3,1
 
+    /**
+     * 这题的前提是数组的size为n，元素范围为[1,n]
+     * 核心思想是给所有出现过的数标为负
+     * 那剩下的为正的数就是没出现过的
+     */
     public List<Integer> findDisappearedNumbers(int[] nums) {
         List<Integer> ret = new ArrayList<Integer>();
 
-        for(int i = 0; i < nums.length; i++) {
+        for (int i = 0; i < nums.length; i++) {
             int val = Math.abs(nums[i]) - 1;
-            if(nums[val] > 0) {
+            if (nums[val] > 0) {
                 nums[val] = -nums[val];
             }
         }
 
-        for(int i = 0; i < nums.length; i++) {
-            if(nums[i] > 0) {
-                ret.add(i+1);
+        for (int i = 0; i < nums.length; i++) {
+            if (nums[i] > 0) {
+                ret.add(i + 1);
             }
         }
         return ret;

test/src/main/java/com/inuker/test/main.java

@@ -1,5 +1,6 @@
 package com.inuker.test;
 
+import com.inuker.solution.FindAllNumbersDisappearedInAnArray;
 import com.inuker.solution.MinimumSizeSubarraySum;
 import com.inuker.solution.NextPermutation;
 import com.inuker.solution.SearchForARange;
@@ -31,9 +32,10 @@ public class main {
 
     public static void main(String[] args) {
         int[] arr = new int[]{
-                1, 2, 3, 4, 5
+                4,3,2,7,8,2,3,1
         };
-        int len = new MinimumSizeSubarraySum().minSubArrayLen2(15, arr);
-        System.out.println(len);
+        for (int n : new FindAllNumbersDisappearedInAnArray().findDisappearedNumbers(arr)) {
+            System.out.print(n + " ");
+        }
     }
 }