3. 3Sum

Author: whewchews

3sum/whewchews.ts

@@ -0,0 +1,33 @@
+function threeSum(nums: number[]): number[][] {
+  let result: [number, number, number][] = [];
+  const TARGET = 0;
+  // TC: O(NlogN)
+  nums.sort((a, b) => a - b);
+
+  for (let i = 0; i < nums.length - 2; i++) {
+    if (i > 0 && nums[i] === nums[i - 1]) continue;
+
+    let left = i + 1;
+    let right = nums.length - 1;
+
+    while (left < right) {
+      let sum = nums[i] + nums[left] + nums[right];
+
+      if (sum === TARGET) {
+        result.push([nums[i], nums[left], nums[right]]);
+        while (nums[left] === nums[left + 1]) left++;
+        while (nums[right] === nums[right - 1]) right--;
+        left++;
+        right--;
+      } else if (sum < TARGET) {
+        left++;
+      } else {
+        right--;
+      }
+    }
+  }
+
+  return result;
+}
+// TC: O(n^2)
+// SC: O(n)