3sum solution

Author: 이호찬

3sum/lhc0506.js

@@ -0,0 +1,50 @@
+/**
+ * @param {number[]} nums
+ * @return {number[][]}
+ */
+var threeSum = function(nums) {
+    const result = [];
+    const numsMap = {};
+
+    nums.forEach((num, index) => {
+        numsMap[num] = (numsMap[num] || 0) + 1;
+
+    });
+
+    for (let i = 0; i < nums.length - 1; i++) {
+        for (let j = i + 1; j < nums.length; j++) {
+            const a = nums[i];
+            const b = nums[j];
+            const targetNum = -(a + b);
+
+            if (!numsMap[targetNum]) {
+                continue;
+            }
+
+            if ((targetNum === a || targetNum === b) && numsMap[targetNum] === 1) {
+                continue;
+            }
+
+            if (targetNum === a && targetNum === b && numsMap[targetNum] <= 2) {
+                continue;
+            }
+
+            const triplet = [a, b, targetNum].sort((x, y) => x - y);
+            const key = triplet.join(',');
+
+            if (seen.has(key)) {
+                continue;
+            }
+
+            seen.add(key);
+
+            result.push(triplet);
+        }
+    }
+
+    return result;
+};
+
+
+//시간 복잡도 O(n²) , 공간 복잡도 O(n²) 라고 생각했는데 Time Limit Exceeded 에러 발생
+// 추후 다시 풀어볼 예정