LeetCode Count Complete Tree Nodes，leetcodenodes

LeetCode Count Complete Tree Nodes，leetcodenodes
LeetCode Count Complete Tree Nodes題目

思路

這個樹會灰常的大；
先沿著左右兩遍計算深度，如果深度一樣直接代公式算；
如果深度不一樣，那就找最下面一層的斷點；

代碼

int maxD, num;int calDeepFromRight(struct TreeNode* root) {    int ans = 0;    while (root) {        ans++;        root = root->right;    }    return ans;}int calDeepFromLeft(struct TreeNode* root) {    int ans = 0;    while (root) {        ans++;        root = root->left;    }    return ans;}void findBreakPoint(struct TreeNode* root, int pos, int deep) {    if (num != -1) return;    if (root == NULL && deep == maxD) {        num = 1;        int base = 1;        for (int i = 1; i < deep - 1; i++) num += (base *= 2);        num += pos;        return;    }    else {        if (root == NULL) return;        findBreakPoint(root->left, pos * 2, deep + 1);        findBreakPoint(root->right, pos * 2 + 1, deep + 1);    }}int countNodes(struct TreeNode* root) {    int ld = calDeepFromLeft(root), rd = calDeepFromRight(root);    maxD = ld;    if (ld == rd) {        if (ld == 0) return 0;        int base = 1;        num = 1;        for (int i = 1; i < ld; i++) num += (base *= 2);    }    else {        num = -1;        findBreakPoint(root, 0, 1);    }    return num;}