solve: 3 sum

Author: tolluset

3sum/tolluset.ts

@@ -0,0 +1,56 @@
+/*
+ * TC: O(n^2)
+ * SC: O(n)
+ * */
+function threeSum(nums: number[]): number[][] {
+  const n = nums.length;
+  const res: number[][] = [];
+
+  nums.sort((a, b) => a - b);
+
+  for (let i = 0; i < n - 2; i++) {
+    if (i > 0 && nums[i] === nums[i - 1]) {
+      continue;
+    }
+
+    let left = i + 1,
+      right = n - 1;
+
+    while (left < right) {
+      const sum = nums[i] + nums[left] + nums[right];
+
+      if (sum === 0) {
+        res.push([nums[i], nums[left], nums[right]]);
+
+        while (nums[left] === nums[left + 1]) {
+          left++;
+        }
+
+        while (nums[right] === nums[right - 1]) {
+          right++;
+        }
+
+        left++;
+        right--;
+
+        continue;
+      }
+
+      if (sum < 0) {
+        left++;
+
+        continue;
+      }
+
+      right--;
+    }
+  }
+
+  return res;
+}
+
+const tc1 = threeSum([-1, 0, 1, 2, -1, -4]); // [[-1,-1,2],[-1,0,1]]
+console.info("🚀 : tolluset.ts:39: tc1=", tc1);
+
+const tc2 = threeSum([0, 0, 0]); // [[0,0,0]]
+console.info("🚀 : tolluset.ts:42: tc2=", tc2);