daily 30일차 2Q 지호

Jiho/Day28/Leetcode_70. Climbing Stairs.js

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+var climbStairs = function (n) {
+  let arr = new Array(n + 1);
+  arr[1] = 1;
+  arr[2] = 2;
+  for (let i = 3; i <= n; i++) {
+    arr[i] = arr[i - 1] + arr[i - 2];
+  }
+  return arr[n];
+};
+
+console.log(climbStairs(10));

Jiho/Day28/Leetcode_746. Min Cost Climbing Stairs.js

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+var minCostClimbingStairs = function (cost) {
+  for (let i = cost.length - 3; i >= 0; i--) {
+    cost[i] += Math.min(cost[i + 1], cost[i + 2]);
+  }
+
+  return Math.min(cost[0], cost[1]);
+};

Jiho/Day29/Leetcode_198. House Robber.js

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+var rob = function (nums) {
+  const len = nums.length;
+
+  let arr = new Array(len);
+  arr[0] = nums[0];
+  arr[1] = Math.max(nums[0], nums[1]);
+  let i;
+  for (i = 2; i < len; i++) {
+    arr[i] = Math.max(arr[i - 1], arr[i - 2] + nums[i]);
+  }
+
+  return arr[len - 1];
+};
+
+console.log(rob([2, 1]));
+
+// DP

Jiho/Day29/Leetcode_213. House Robber II.js

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+var rob2 = function (nums) {
+  const getMax = (nums) => {
+    let prevRob = 0,
+      maxRob = 0;
+
+    for (let num of nums) {
+      let temp = Math.max(maxRob, prevRob + num);
+      prevRob = maxRob;
+      maxRob = temp;
+    }
+
+    return maxRob;
+  };
+
+  if (nums.length === 1) return nums[0];
+  return Math.max(getMax(nums.slice(0, -1)), getMax(nums.slice(1)), nums[0]);
+};
+
+console.log(rob2([1, 2, 3, 1]));

Jiho/Day30/Leetcode_34. Find First and Last Position of Element in Sorted Array.js

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+var searchRange = function (nums, target) {
+  let arr = [];
+  let [left, right] = [0, nums.length - 1];
+  const find_match = (l, r) => {
+    while (l <= r) {
+      const mid = Math.floor((l + r) / 2);
+      const val = nums[mid];
+      if (val > target) {
+        r = mid - 1;
+      } else if (val < target) {
+        l = mid + 1;
+      } else {
+        arr.push(mid);
+        find_match(l, mid - 1);
+        find_match(mid + 1, r);
+        return;
+      }
+    }
+  };
+
+  find_match(left, right);
+
+  return arr.length === 0 ? [-1, -1] : [Math.min(...arr), Math.max(...arr)];
+};
+
+console.log(searchRange([], 6));

Jiho/Day30/Leetcode_4. Median of Two Sorted Arrays.js

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+var findMedianSortedArrays = function (nums1, nums2) {
+  let arr = [...nums1, ...nums2];
+  arr.sort((a, b) => a - b);
+  const len = arr.length;
+  // 홀수
+  if (len % 2) {
+    return arr[Math.floor(len / 2)];
+  }
+  // 짝수
+  else {
+    const mid = Math.floor(len / 2);
+    return (arr[mid] + arr[mid - 1]) / 2;
+  }
+};
+
+console.log(findMedianSortedArrays([1, 3], [2, 4, 5]));