[환미니니] Week7 문제풀이

longest-substring-without-repeating-characters/hwanmini.js

@@ -0,0 +1,28 @@
+// 시간복잡도: O(n)
+// 공간복잡도: O(n)
+
+/**
+ * @param {string} s
+ * @return {number}
+ */
+var lengthOfLongestSubstring = function(s) {
+    let maxCount = 0;
+    const map = new Map()
+
+    let leftIdx = 0;
+    for (let rightIdx = 0 ; rightIdx < s.length; rightIdx++) {
+        const char = s[rightIdx]
+        if (map.has(char) && map.get(char) >= leftIdx) leftIdx = map.get(char) + 1;
+        map.set(char, rightIdx)
+        maxCount = Math.max(maxCount, rightIdx - leftIdx + 1)
+    }
+
+    return maxCount
+};
+
+
+console.log(lengthOfLongestSubstring("abcabcbb"))
+console.log(lengthOfLongestSubstring("bbbbb"))
+console.log(lengthOfLongestSubstring("pwwkew"))
+console.log(lengthOfLongestSubstring("abba"))
+

number-of-islands/hwanmini.js

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+// 시간복잡도: O(n * m)
+// 공간복잡도: O(n * m)
+
+const dr = [1,-1,0,0]
+const dc = [0,0,-1, 1]
+
+const isValidMove = (grid, n_row, n_col) => {
+    return n_row >= 0 && n_row < grid.length && n_col >= 0 && n_col < grid[0].length && grid[n_row][n_col] !== '0'
+}
+
+
+/**
+ * @param {character[][]} grid
+ * @return {number}
+ */
+var numIslands = function(grid) {
+    let islandCount = 0;
+
+    const bfs = (row, col) => {
+        const que = [[row,col]]
+
+        while (que.length) {
+            const [row, col] = que.pop()
+
+            for (let i = 0 ; i < dr.length; i++) {
+                const n_row = row + dr[i]
+                const n_col = col + dc[i]
+
+                if (isValidMove(grid, n_row, n_col)) {
+                    que.push([n_row, n_col])
+                }
+            }
+
+            grid[row][col] = '0'
+
+        }
+
+        islandCount += 1
+    }
+
+
+    for (let row = 0; row < grid.length; row++) {
+        for (let col = 0; col < grid[row].length; col++) {
+            if (grid[row][col] !== '0') bfs(row, col)
+        }
+    }
+
+
+    return islandCount
+};
+
+console.log(numIslands([["1","1","1","1","0"],["1","1","0","1","0"],["1","1","0","0","0"],["0","0","0","0","0"]]))

reverse-linked-list/hwanmini.js

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+// 시간복잡도: O(n)
+// 공간복잡도: O(1)
+
+/**
+ * Definition for singly-linked list.
+ * function ListNode(val, next) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.next = (next===undefined ? null : next)
+ * }
+ */
+/**
+ * @param {ListNode} head
+ * @return {ListNode}
+ */
+var reverseList = function(head) {
+    let curNode = head
+    let preNode = null
+
+    while (curNode) {
+        const nextNode = curNode.next
+        curNode.next = preNode
+        preNode = curNode
+        curNode = nextNode
+    }
+
+
+    return preNode
+};

set-matrix-zeroes/hwamini.js

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+// 시간복잡도: O((n * m) * (n + m))
+// 공간복잡도: O(n * m)
+
+/**
+ * @param {number[][]} matrix
+ * @return {void} Do not return anything, modify matrix in-place instead.
+ */
+var setZeroes = function(matrix) {
+    const zeroIndexes = []
+
+    for (let row = 0; row < matrix.length; row++) {
+        for (let col = 0; col < matrix[row].length; col++) {
+            if (matrix[row][col] === 0) {
+                zeroIndexes.push([row,col])
+            }
+        }
+    }
+
+    while (zeroIndexes.length) {
+        const [row, col] = zeroIndexes.pop()
+
+        for (let i = 0; i < matrix[0].length; i++) {
+            matrix[row][i] = 0
+        }
+
+        for (let j = 0; j < matrix.length; j++) {
+            matrix[j][col] = 0
+        }
+
+    }
+
+    return matrix
+};
+
+console.log(setZeroes([
+    [1,1,1],
+    [1,0,1],
+    [1,1,1]]))
+console.log(setZeroes([[0,1,2,0],[3,4,5,2],[1,3,1,5]]))