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Diffstat (limited to 'count_num_good_nodes.c')
-rw-r--r-- | count_num_good_nodes.c | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/count_num_good_nodes.c b/count_num_good_nodes.c new file mode 100644 index 0000000..44879ed --- /dev/null +++ b/count_num_good_nodes.c @@ -0,0 +1,74 @@ +// 3249. Count the Number of Good Nodes +#include "leetcode.h" + +/* + * there is an undirected tree with 'n' nodes labeled from 0 to 'n - 1', and + * rooted at node 0. you are given a 2d integer array 'edges' of length 'n - 1' + * where 'edges[i] = [a_i, b_i]' indicates that there is an edge between nodes + * 'a_i' and 'b_i' in the tree. a node is good if all the subtrees rooted at is + * children have the same size. return the number of good nodes in the given + * tree. a subtree of 'treeName' is a tree consisting of a node in 'treeName' + * and all of its descendants. + */ + +struct map { + int *next; + int cnt; +}; + +int dfs(struct map *m, int fa, int curr, int *res) { + int n = m[curr].cnt; + if (n == 1 && curr) { + (*res)++; + return 1; + } + int prev = -1, sum = 0; + bool flag = true; + for (int i = 0; i < n; i++) { + int next = m[curr].next[i]; + if (next != fa) { + int x = dfs(m, curr, next, res); + if (prev == -1) + prev = x; + else if (x != prev) + flag = false; + sum += x; + } + } + *res += flag; + return sum + 1; +} + +int countGoodNodes(int **edges, int edgesSize, int *edgesColSize) { + int n = edgesSize + 1; + int *cnt_child = (int *)calloc(n, sizeof(int)); + for (int i = 0; i < edgesSize; i++) { + int n1 = edges[i][0], n2 = edges[i][1]; + cnt_child[n1]++; + cnt_child[n2]++; + } + struct map *m = (struct map *)calloc(n, sizeof(struct map)); + for (int i = 0; i < n; i++) + m[i].next = (int *)calloc(cnt_child[i], sizeof(int)); + for (int i = 0; i < edgesSize; i++) { + int n1 = edges[i][0], n2 = edges[i][1]; + m[n1].next[m[n1].cnt++] = n2; + m[n2].next[m[n2].cnt++] = n1; + } + int ans = 0; + dfs(m, -1, 0, &ans); + return ans; +} + +int main() { + int e1i[6][2] = {{0, 1}, {0, 2}, {1, 3}, {1, 4}, {2, 5}, {2, 6}}; + int e2i[8][2] = {{0, 1}, {1, 2}, {2, 3}, {3, 4}, + {0, 5}, {1, 6}, {2, 7}, {3, 8}}; + struct two_d_arr e1, e2; + two_d_arr_init(&e1, 6, 2, e1i); + two_d_arr_init(&e2, 8, 2, e2i); + printf("%d\n", countGoodNodes(e1.arr, e1.row_size, e1.col_size)); // expect: 7 + printf("%d\n", countGoodNodes(e2.arr, e2.row_size, e2.col_size)); // expect: 6 + two_d_arr_free(&e1); + two_d_arr_free(&e2); +} |