// 1380. Lucky Numbers in a Matrix #include "leetcode.h" /* * given an 'm * n' matrix of distinct numbers, return all lucky numbers in the * matrix in any order. a lucky number is an element of the matrix such that it * is the minimum element in its row and maximum in its column */ int *luckyNumbers(int **matrix, int matrixSize, int *matrixColSize, int *returnSize) { int n = 0, *ans = (int *)malloc((matrixSize + 1) * sizeof(int)); for (int r = 0; r < matrixSize; r++) for (int c = 0; c < *matrixColSize; c++) { int curr = matrix[r][c]; bool flag1 = false, flag2 = false; for (int i = 0; !flag1 && i < *matrixColSize; i++) if (matrix[r][i] < curr) flag1 = true; for (int i = 0; !flag2 && i < matrixSize; i++) if (matrix[i][c] > curr) flag2 = true; if (!flag1 && !flag2) { ans[n] = curr; n++; } } *returnSize = n; return ans; } int main() { int m1[3][3] = {{3, 7, 8}, {9, 11, 13}, {15, 16, 17}}, m2[3][4] = {{1, 10, 4, 2}, {9, 3, 8, 7}, {15, 16, 17, 12}}, m3[2][2] = {{7, 8}, {1, 2}}; int mcs1[] = {3, 3, 3}, mcs2[] = {3, 3, 3, 3}, mcs3[] = {2, 2}, rs1, rs2, rs3; int *ln1 = luckyNumbers((int **)m1, ARRAY_SIZE(m1), mcs1, &rs1); int *ln2 = luckyNumbers((int **)m2, ARRAY_SIZE(m2), mcs2, &rs2); int *ln3 = luckyNumbers((int **)m3, ARRAY_SIZE(m3), mcs3, &rs3); for (int i = 0; i < rs1; i++) printf("%d ", ln1[i]); // expect: 15 printf("\n"); for (int i = 0; i < rs1; i++) printf("%d ", ln1[i]); // expect: 15 printf("\n"); for (int i = 0; i < rs2; i++) printf("%d ", ln2[i]); // expect: 12 for (int i = 0; i < rs3; i++) printf("%d ", ln3[i]); // expect: 7 printf("\n"); free(ln1), free(ln2), free(ln3); }