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begeekmyfriend · begeekmyfriend · commit acdf017d924f · 2020-06-23T23:56:28.000+08:00
Signed-off-by: begeekmyfriend &lt;begeekmyfriend@gmail.com&gt;
diff --git a/039_combination_sum/combination_sum.c b/039_combination_sum/combination_sum.c
@@ -13,9 +13,6 @@ static void dfs(int *nums, int size, int start, int target, int *stack,
         (*count)++;
     } else if (target > 0) {
         for (i = start; i < size; i++) {
-            if (i > 0 && nums[i] == nums[i - 1]) {
-                continue;
-            }
             stack[len] = nums[i];
             dfs(nums, size, i, target - nums[i], stack, len + 1, results, column_sizes, count);
         }
diff --git a/040_combination_sum_ii/combination_sum.c b/040_combination_sum_ii/combination_sum.c
@@ -20,9 +20,14 @@ static void dfs(int *nums, int size, int start, int target, int *solution, int l
     } else if (target > 0) {
         for (i = start; i < size; i++) {
             if (!used[i]) {
-                if (i > 0 && !used[i - 1] && nums[i - 1] == nums[i]) continue;
+                if (i > 0 && !used[i - 1] && nums[i - 1] == nums[i]) {
+                    /* Forbid same elements in same level */
+                    /* Used marks allow same elements in different levels */
+                    continue;
+                }
                 used[i] = true;
                 solution[len] = nums[i];
+                /* i + 1 limits the selecting range in following levels */
                 dfs(nums, size, i + 1, target - nums[i], solution, len + 1, used, results, count, column_sizes);
                 used[i] = false;
             }
diff --git a/047_permutations_ii/permutations.c b/047_permutations_ii/permutations.c
@@ -20,7 +20,11 @@ static void dfs(int *nums, int size, bool *used, int *stack,
     } else {
         for (i = 0; i < size; i++) {
             if (!used[i]) {
-                if (i > 0 && nums[i] == nums[i - 1] && !used[i - 1]) continue;
+                if (i > 0 && nums[i] == nums[i - 1] && !used[i - 1]) {
+                    /* Forbid same elements on same level */
+                    /* Used marks allow same elements in different levels */
+                    continue;
+                }
                 used[i] = true;
                 stack[len] = nums[i];
                 dfs(nums, size, used, stack, len + 1, results, count, col_size);
@@ -33,7 +37,7 @@ static void dfs(int *nums, int size, bool *used, int *stack,
 /**
  * Return an array of arrays of size *returnSize.
  * The sizes of the arrays are returned as *returnColumnSizes array.
- * Note: Both returned array and *columnSizes array must be malloced, assume caller calls free().
+ * Note: Both returned array and *returnColumnSizes array must be malloced, assume caller calls free().
  */
 static int **permute(int* nums, int numsSize, int* returnSize, int **returnColumnSize)
 {
diff --git a/090_subsets_ii/subsets.c b/090_subsets_ii/subsets.c
@@ -19,10 +19,13 @@ static void dfs(int *nums, int size, int start, int *buf, int level,
     for (i = start; i < size; i++) {
         if (!used[i]) {
             if (i > 0 && !used[i - 1] && nums[i - 1] == nums[i]) {
+                /* Forbid same elements on same level */
+                /* Used marks allow same elements in different levels */
                 continue;
             }
             used[i] = true;
             buf[level] = nums[i];
+            /* i + 1 limits the selecting range in following levels */
             dfs(nums, size, i + 1, buf, level + 1, used, sets, count, sizes);
             used[i] = false;
         }

Original file line number	Diff line number	Diff line change
`@@ -19,10 +19,13 @@ static void dfs(int nums, int size, int start, int buf, int level,`
`19`	`19`	`for (i = start; i < size; i++) {`
`20`	`20`	`if (!used[i]) {`
`21`	`21`	`if (i > 0 && !used[i - 1] && nums[i - 1] == nums[i]) {`
	`22`	`+ /* Forbid same elements on same level */`
	`23`	`+ /* Used marks allow same elements in different levels */`
`22`	`24`	`continue;`
`23`	`25`	`}`
`24`	`26`	`used[i] = true;`
`25`	`27`	`buf[level] = nums[i];`
	`28`	`+ /* i + 1 limits the selecting range in following levels */`
`26`	`29`	`dfs(nums, size, i + 1, buf, level + 1, used, sets, count, sizes);`
`27`	`30`	`used[i] = false;`
`28`	`31`	`}`