diff --git "a/problems/0040.347円273円204円345円220円210円346円200円273円345円222円214円II.md" "b/problems/0040.347円273円204円345円220円210円346円200円273円345円222円214円II.md"
index 99577f0cdf..417f4a6d4d 100644
--- "a/problems/0040.347円273円204円345円220円210円346円200円273円345円222円214円II.md"
+++ "b/problems/0040.347円273円204円345円220円210円346円200円273円345円222円214円II.md"
@@ -258,40 +258,45 @@ public:
 **使用标记数组**
 ```Java
 class Solution {
- List<list<integer>> lists = new ArrayList<strong>();
- Deque<integer> deque = new LinkedList<strong>();
- int sum = 0;
-
- public List<list<integer>> combinationSum2(int[] candidates, int target) {
- //为了将重复的数字都放到一起,所以先进行排序
- Arrays.sort(candidates);
- //加标志数组,用来辅助判断同层节点是否已经遍历
- boolean[] flag = new boolean[candidates.length];
- backTracking(candidates, target, 0, flag);
- return lists;
- }
+ LinkedList<integer> path = new LinkedList<strong>();
+ List<list<integer>> ans = new ArrayList<strong>();
+ boolean[] used;
+ int sum = 0;
 
- public void backTracking(int[] arr, int target, int index, boolean[] flag) {
- if (sum == target) {
- lists.add(new ArrayList(deque));
- return;
- }
- for (int i = index; i < arr.length && arr[i] + sum <= target; i++) { - //出现重复节点,同层的第一个节点已经被访问过,所以直接跳过 - if (i> 0 && arr[i] == arr[i - 1] && !flag[i - 1]) {
- continue;
- }
- flag[i] = true;
- sum += arr[i];
- deque.push(arr[i]);
- //每个节点仅能选择一次,所以从下一位开始
- backTracking(arr, target, i + 1, flag);
- int temp = deque.pop();
- flag[i] = false;
- sum -= temp;
- }
+ public List<list<integer>> combinationSum2(int[] candidates, int target) {
+ used = new boolean[candidates.length];
+ // 加标志数组,用来辅助判断同层节点是否已经遍历
+ Arrays.fill(used, false);
+ // 为了将重复的数字都放到一起,所以先进行排序
+ Arrays.sort(candidates);
+ backTracking(candidates, target, 0);
+ return ans;
+ }
+
+ private void backTracking(int[] candidates, int target, int startIndex) {
+ if (sum == target) {
+ ans.add(new ArrayList(path));
+ }
+ for (int i = startIndex; i < candidates.length; i++) { + if (sum + candidates[i]> target) {
+ break;
+ }
+ // 出现重复节点,同层的第一个节点已经被访问过,所以直接跳过
+ if (i> 0 && candidates[i] == candidates[i - 1] && !used[i - 1]) {
+ continue;
+ }
+ used[i] = true;
+ sum += candidates[i];
+ path.add(candidates[i]);
+ // 每个节点仅能选择一次,所以从下一位开始
+ backTracking(candidates, target, i + 1);
+ used[i] = false;
+ sum -= candidates[i];
+ path.removeLast();
 }
+ }
 }
+
 ```
 **不使用标记数组**
 ```Java
diff --git "a/problems/0216.347円273円204円345円220円210円346円200円273円345円222円214円III.md" "b/problems/0216.347円273円204円345円220円210円346円200円273円345円222円214円III.md"
index 1ef278ff2d..964faceebb 100644
--- "a/problems/0216.347円273円204円345円220円210円346円200円273円345円222円214円III.md"
+++ "b/problems/0216.347円273円204円345円220円210円346円200円273円345円222円214円III.md"
@@ -260,6 +260,37 @@ class Solution {
 		}
 	}
 }
+
+// 上面剪枝 i <= 9 - (k - path.size()) + 1; 如果还是不清楚 +// 也可以改为 if (path.size()> k) return; 执行效率上是一样的
+class Solution {
+ LinkedList<integer> path = new LinkedList<strong>();
+ List<list<integer>> ans = new ArrayList<strong>();
+ public List<list<integer>> combinationSum3(int k, int n) {
+ build(k, n, 1, 0);
+ return ans;
+ }
+
+ private void build(int k, int n, int startIndex, int sum) {
+ 
+ if (sum> n) return;
+
+ if (path.size()> k) return;
+
+ if (sum == n && path.size() == k) {
+ ans.add(new ArrayList<strong>(path));
+ return;
+ }
+ 
+ for(int i = startIndex; i <= 9; i++) {
+ path.add(i);
+ sum += i;
+ build(k, n, i + 1, sum);
+ sum -= i;
+ path.removeLast();
+ }
+ }
+}
 ```
 
 其他方法
diff --git "a/problems/0530.344円272円214円345円217円211円346円220円234円347円264円242円346円240円221円347円232円204円346円234円200円345円260円217円347円273円235円345円257円271円345円267円256円.md" "b/problems/0530.344円272円214円345円217円211円346円220円234円347円264円242円346円240円221円347円232円204円346円234円200円345円260円217円347円273円235円345円257円271円345円267円256円.md"
index 809f500bff..4b70a59500 100644
--- "a/problems/0530.344円272円214円345円217円211円346円220円234円347円264円242円346円240円221円347円232円204円346円234円200円345円260円217円347円273円235円345円257円271円345円267円256円.md"
+++ "b/problems/0530.344円272円214円345円217円211円346円220円234円347円264円242円346円240円221円347円232円204円346円234円200円345円260円217円347円273円235円345円257円271円345円267円256円.md"
@@ -233,7 +233,7 @@ class Solution:
 else: # 逐一处理节点
 cur = stack.pop()
 if pre: # 当前节点和前节点的值的差值
- result = min(result, cur.val - pre.val)
+ result = min(result, abs(cur.val - pre.val))
 pre = cur
 cur = cur.right
 return result
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