[환미니니] Week12 Solutions

number-of-connected-components-in-an-undirected-graph/hwanmini.js

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+// V는 정점, E는 간선
+// 시간 복잡도: O(V + E)
+// 공간 복잡도: O(V + E)
+
+class Solution {
+    /**
+     * @param {number} n
+     * @param {number[][]} edges
+     * @returns {number}
+     */
+    countComponents(n, edges) {
+        const visited = Array.from({length: n}, () => false);
+        const graph = new Map();
+
+        for (const [v, d] of edges) {
+            if (!graph.has(v)) graph.set(v, []);
+            if (!graph.has(d)) graph.set(d, []);
+
+            graph.get(v).push(d);
+            graph.get(d).push(v);
+        }
+
+        const dfs = (node) => {
+            visited[node] = true
+            for (let nei of graph.get(node) || []) {
+                if (!visited[nei]) dfs(nei)
+            }
+        }
+
+        let count = 0;
+        for (let i = 0; i < n; i++) {
+            if (!visited[i]) {
+                dfs(i);
+                count++;
+            }
+        }
+
+
+        return count
+    }
+}

same-tree/hwanmini.js

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+// 시간복잡도: O(n)
+// 공간복잡도: O(n)
+
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val, left, right) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.left = (left===undefined ? null : left)
+ *     this.right = (right===undefined ? null : right)
+ * }
+ */
+/**
+ * @param {TreeNode} p
+ * @param {TreeNode} q
+ * @return {boolean}
+ */
+var isSameTree = function(p, q) {
+    if ((p && !q) || (!p && q)) return false;
+    if (!p || !q) return true
+    if (p.val === q.val) return isSameTree(p.left, q.left) && isSameTree(p.right, q.right)
+    return false
+};
+