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-rw-r--r--combination_sum2.c60
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diff --git a/combination_sum2.c b/combination_sum2.c
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+++ b/combination_sum2.c
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+// 40. Combination Sum II
+#include "leetcode.h"
+
+/*
+ * given a collection of candidate numbers and a target number, find all unique
+ * combinations in 'candidates' where the candidate numbers sum to 'target'.
+ * each number in 'candidates' may only be used once
+ */
+
+int cmp(const void *a, const void *b) { return *(int *)a - *(int *)b; }
+
+void dfs(int *candidates, int candidatesSize, int target, int idx, int *curr,
+ int currSize, int *returnSize, int **returnColumnSizes, int ***res) {
+ int prev = 0;
+ for (int i = idx; i < candidatesSize; i++) {
+ if (candidates[i] == target) {
+ (*returnSize)++;
+ *res = (int **)realloc(*res, (*returnSize) * sizeof(int *));
+ (*res)[(*returnSize) - 1] = (int *)malloc((currSize + 1) * sizeof(int));
+ memcpy((*res)[(*returnSize) - 1], curr, currSize * sizeof(int));
+ (*res)[(*returnSize) - 1][currSize] = candidates[i];
+ (*returnColumnSizes) =
+ (int *)realloc((*returnColumnSizes), (*returnSize) * sizeof(int));
+ (*returnColumnSizes)[(*returnSize) - 1] = currSize + 1;
+ break;
+ } else if (candidates[i] <= (target / 2) && candidates[i] != prev) {
+ curr[currSize] = candidates[i];
+ dfs(candidates, candidatesSize, target - candidates[i], i + 1, curr,
+ currSize + 1, returnSize, returnColumnSizes, res);
+ prev = candidates[i];
+ } else if (candidates[i] > target)
+ break;
+ }
+}
+
+int **combinationSum2(int *candidates, int candidatesSize, int target,
+ int *returnSize, int **returnColumnSizes) {
+ qsort(candidates, candidatesSize, sizeof(int), cmp);
+ int *curr = (int *)malloc(100 * sizeof(int)), currSize = 0;
+ int **ans = (int **)malloc(sizeof(int *));
+ (*returnColumnSizes) = (int *)malloc(sizeof(int));
+ (*returnSize) = 0;
+ dfs(candidates, candidatesSize, target, 0, curr, currSize, returnSize,
+ returnColumnSizes, &ans);
+ free(curr);
+ return ans;
+}
+
+int main() {
+ int c1[] = {10, 1, 2, 7, 6, 1, 5}, c2[] = {2, 5, 2, 1, 2}, rs1, rs2;
+ int *rcs1 = (int *)malloc(ARRAY_SIZE(c1) * sizeof(int));
+ int *rcs2 = (int *)malloc(ARRAY_SIZE(c2) * sizeof(int));
+ int **cs21 = combinationSum2(c1, ARRAY_SIZE(c1), 8, &rs1, (int **)rcs1);
+ int **cs22 = combinationSum2(c2, ARRAY_SIZE(c2), 5, &rs2, (int **)rcs2);
+ for (int i = 0; i < rs2; i++)
+ for (int j = 0; j < rcs2[i]; j++)
+ printf("%d ", cs22[i][j]);
+ printf("\n");
+ free(cs21), free(cs22), free(rcs1), free(rcs2);
+}