// 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); }