题目：329. 矩阵中的最长递增路径 - 力扣（LeetCode）

数据规模很小，排序就够了

struct Node {int x;int y;int val;Node* up = nullptr;Node* down = nullptr;Node* left = nullptr;Node* right = nullptr;int length = 0;Node(int _x, int _y, int _v) {x = _x;y = _y;val = _v;}
};
bool myComp(Node* a, Node* b) {return a->val < b->val;
}
class Solution {
public:int longestIncreasingPath(vector<vector<int>>& matrix) {vector<Node*> arr;int upIdx, leftIdx;for (int i = 0; i < matrix.size(); i++) {vector<int>& t = matrix[i];for (int j = 0; j < t.size(); j++) {Node* node = new Node(i, j, t[j]);arr.push_back(node);if (i > 0) {upIdx = (i - 1) * t.size() + j;node->up = arr[upIdx];arr[upIdx]->down = node;}if (j > 0) {leftIdx = i * t.size() + j - 1;node->left = arr[leftIdx];arr[leftIdx]->right = node;}}}sort(arr.begin(), arr.end(), myComp);int max;int ret = 1;for (int i = 0; i < arr.size(); i++) {Node* node = arr[i];max = 0;if (node->left && node->left->val < node->val && node->left->length > max) {max = node->left->length;}if (node->right && node->right->val < node->val && node->right->length > max) {max = node->right->length;}if (node->up && node->up->val < node->val && node->up->length > max) {max = node->up->length;}if (node->down && node->down->val < node->val && node->down->length > max) {max = node->down->length;}node->length = max + 1;if (node->length > ret) {ret = node->length;}}return ret;}
};