| 功能 | C语言 | C++ | Java |
| 比较两数的大小 | fmax(a, b) | max(a, b) | Math.max(a, b) |
| 链表定义 | struct ListNode* dummy = malloc(sizeof(struct ListNode)); // 申请空间 dummy->next = head; dummy->val = 0; | ListNode* dummy = new ListNode(0, head); | ListNode dummy = new ListNode(0, head); |
| 释放内存 | free(node); | delete(node); | |
| 数组申请使用 | int* arr = (int*)calloc(10, sizeof(int)); arr[i] = 1; | int arr[10]; arr[i] = 1; | int[] arr = new int[10]; arr[i] = 1; |
| 绝对值 | abs() | abs() | Math.abs() |
| int最值 | INT_MIN INT_MAX | INT_MIN INT_MAX | Integer.MIN_VALUE Integer.MAX_VALUE |
| long最值 | LONG_MIN LONG_MAX | LONG_MIN LONG_MAX | Long.MIN_VALUE Long.MAX_VALUE |
| kong | NULL | nullptr | null |
| 声明二叉树 | struct TreeNode* node = malloc(sizeof(struct TreeNode)); node->left = NULL; node->right = NULL; node->val = 0; | TreeNode* node = new TreeNode(); node->left = nullptr; node->right = nullptr; node->val = 0; | TreeNode node = new TreeNode(); node.left = null; node.right = null; node.val = 0; |
| 声明结构体 | struct Height { int max_height; bool isBST; }; | struct Height { int a; bool b; Height(int max, bool isB) : a(max), b(isB) {} }; | class Height { int a; boolean b; public Height(int max, boolean isB) { a = max; b = isB; } } |
| 数组初值 | 数组的初值是随机的 | 数组的初值默认0 | 数组的初值默认0 |
| 二维数组 | int dp[N][2]; | vector | int[][] dp = new int[N][2]; |
