// 1128. Number of Equivalent Domino Pairs #include "leetcode.h" /* * given a list of 'dominoes', 'dominoes[i] = [a, b]' is equivalent to * 'dominoes[j] = [c, d]' if and only if either 'a == c' and 'b == d' or 'a == * d' and 'b == c'. return the number of pairs '(i, j)' for which '0 <= i < j < * dominoes.length' and 'dominoes[i]' is equivalent to 'dominoes[j]'. */ int numEquivDominoPairs(int **dominoes, int dominoesSize, int *dominoesColSize) { int map[100] = {0}, cnt = 0; for (int i = 0; i < dominoesSize; ++i) { int u = dominoes[i][0], v = dominoes[i][1]; int num = u > v ? v * 10 + u : u * 10 + v; cnt += map[num]; map[num]++; } return cnt; } int main() { int d1i[4][2] = {{1, 2}, {2, 1}, {3, 4}, {5, 6}}; int d2i[5][2] = {{1, 2}, {1, 2}, {1, 1}, {1, 2}, {2, 2}}; struct two_d_arr d1, d2; two_d_arr_init(&d1, ARRAY_SIZE(d1i), ARRAY_SIZE(d1i[0]), d1i); two_d_arr_init(&d2, ARRAY_SIZE(d2i), ARRAY_SIZE(d2i[0]), d2i); printf("%d\n", numEquivDominoPairs(d1.arr, d1.row_size, d1.col_size)); // expect: 1 printf("%d\n", numEquivDominoPairs(d2.arr, d2.row_size, d2.col_size)); // expect: 3 two_d_arr_free(&d1); two_d_arr_free(&d2); }