[juhui-jeong] WEEK 01 solutions #219

contains-duplicate/juhui-jeong.ts

@@ -0,0 +1,16 @@
+/*
+시간 복잡도: O(n)
+공간 복잡도: O(n)
+*/
+function containsDuplicate(nums: number[]): boolean {
+  const seen = new Set<number>();
+
+  for (const num of nums) {
+    if (seen.has(num)) {
+      return true;
+    }
+    seen.add(num);
+  }
+
+  return false;
+}

two-sum/juhui-jeong.ts

@@ -0,0 +1,41 @@
+/*
+시간 복잡도: O(n)
+공간 복잡도: O(n)
+*.
+function twoSum(nums: number[], target: number): number[] {
+  const map = new Map<number, number>();
+
+  for (let i = 0; i < nums.length; i++) {
+    const num = nums[i];
+    const diff = target - num;
+
+    if (map.has(diff)) {
+      return [map.get(diff)!, i];
+    }
+
+    map.set(num, i);
+  }
+
+  return [];
+}
+
+/*
+이전 풀이
+시간 복잡도: O(n²)
+공간 복잡도: O(1)
+function twoSum(nums: number[], target: number): number[] {
+  for (let i = 0; i < nums.length; i++) {
+    for (let j = 0; j < nums.length; j++) {
+      // 동일한 index일 때는 안됨.
+      if (i === j) {
+        continue;
+      }
+      if (nums[i] + nums[j] === target) {
+        return [i, j];
+      }
+    }
+    return [];
+  }
+}
+
+*/