solve(w02): 15. 3Sum

Author: jeongwoo903

3sum/jeongwoo903.js

@@ -0,0 +1,42 @@
+/*
+* 투 포인터 방식 사용
+* 시간 복잡도: O(n^2)
+* 공간 복잡도; O(n^2)
+*/
+
+/**
+ * @param {number[]} nums
+ * @return {number[][]}
+ */
+const threeSum = (nums) => {
+  const sorted = [...nums].sort((a, b) => a - b);
+  const results = [];
+
+  sorted.forEach((val, i) => {
+    if (i > 0 && val === sorted[i - 1]) return;
+
+    let left = i + 1;
+    let right = sorted.length - 1;
+
+    while (left < right) {
+      const sum = val + sorted[left] + sorted[right];
+
+      if (sum === 0) {
+        results.push([val, sorted[left], sorted[right]]);
+
+        // 중복된 left/right 스킵
+        const currentLeft = sorted[left];
+        const currentRight = sorted[right];
+
+        while (left < right && sorted[left] === currentLeft) left++;
+        while (left < right && sorted[right] === currentRight) right--;
+      } else if (sum < 0) {
+        left++;
+      } else {
+        right--;
+      }
+    }
+  });
+
+  return results;
+};