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-rw-r--r--finding_3_digit_even_num.c59
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diff --git a/finding_3_digit_even_num.c b/finding_3_digit_even_num.c
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+// 2094. Finding 3-Digit Even Numbers
+#include "leetcode.h"
+
+/*
+ * you are given an integer 'digits' where each element is a digit. the array
+ * may contain duplicates. you need to find all the unique integers that follow
+ * the given requirements: the integer consists of the concatenation of three
+ * elements from 'digits' in any arbitrary order, the integer does not have
+ * leading zeros, and the integer is even. for example, if the given 'digits'
+ * were '[1, 2, 3]' integers '132' and '312' follow the requirments. return a
+ * sorted array of the unique integers.
+ */
+
+int *findEvenNumbers(int *digits, int digitsSize, int *returnSize) {
+ int hash[10] = {0};
+ for (int i = 0; i < digitsSize; i++)
+ hash[digits[i]]++;
+ int *ans = (int *)malloc(sizeof(int));
+ *returnSize = 0;
+ int idx = 0;
+ for (int i = 100; i < 999; i += 2) {
+ int cnt[10] = {0}, tmp = i;
+ bool flag = true;
+ while (tmp) {
+ cnt[tmp % 10]++;
+ tmp /= 10;
+ }
+ for (int j = 0; j < 10; j++)
+ if (cnt[j] > hash[j]) {
+ flag = false;
+ break;
+ }
+ if (flag) {
+ (*returnSize)++;
+ ans = (int *)realloc(ans, (*returnSize) * sizeof(int));
+ ans[idx++] = i;
+ }
+ }
+ return ans;
+}
+
+int main() {
+ int d1[] = {2, 1, 3, 0}, d2[] = {2, 2, 8, 8, 2}, d3[] = {3, 7, 5};
+ int rs1, *fen1 = findEvenNumbers(d1, ARRAY_SIZE(d1), &rs1);
+ int rs2, *fen2 = findEvenNumbers(d2, ARRAY_SIZE(d2), &rs2);
+ int rs3, *fen3 = findEvenNumbers(d3, ARRAY_SIZE(d3), &rs3);
+ for (int i = 0; i < rs1; i++)
+ printf("%d ", fen1[i]); // expect: 102,120,130,132,210,230,302,310,312,320
+ printf("\n");
+ for (int i = 0; i < rs2; i++)
+ printf("%d ", fen2[i]); // expect: 222,228,282,288,822,828,882
+ printf("\n");
+ for (int i = 0; i < rs3; i++)
+ printf("%d ", fen3[i]); // expect: null
+ printf("\n");
+ free(fen1);
+ free(fen2);
+ free(fen3);
+}