added Problem 16

Author: aQua

Algorithms/0016.3sum-closest/3sum-closest.go

@@ -6,7 +6,6 @@ import (
 )
 
 func threeSumClosest(nums []int, target int) int {
-
 	// 排序后，可以按规律查找
 	sort.Ints(nums)
 	res, delta := 0, math.MaxInt64
@@ -21,45 +20,24 @@ func threeSumClosest(nums []int, target int) int {
 
 		for l < r {
 			s := nums[i] + nums[l] + nums[r]
-			temp := abs(target - s)
 			switch {
-			case temp < delta:
-
+			case s < target:
 				l++
-			case s > 0:
-				// 较大的 r 需要变小
+				if delta > target-s {
+					delta = target - s
+					res = s
+				}
+			case s > target:
 				r--
+				if delta > s-target {
+					delta = s - target
+					res = s
+				}
 			default:
-				res = append(res, []int{nums[i], nums[l], nums[r]})
-				// 为避免重复添加，l 和 r 都需要移动到不同的元素上。
-				l, r = next(nums, l, r)
+				return s
 			}
 		}
 	}
 
 	return res
 }
-
-func next(nums []int, l, r int) (int, int) {
-	for l < r {
-		switch {
-		case nums[l] == nums[l+1]:
-			l++
-		case nums[r] == nums[r-1]:
-			r--
-		default:
-			l++
-			r--
-			return l, r
-		}
-	}
-
-	return l, r
-}
-
-func abs(a int) int {
-	if a > 0 {
-		return a
-	}
-	return -a
-}

Algorithms/0016.3sum-closest/3sum-closest_test.go

@@ -34,7 +34,14 @@ func Test_Problem0016(t *testing.T) {
 			para{[]int{-1, 2, 1, -4}, 1},
 			ans{2},
 		},
-
+		question{
+			para{[]int{-1, 2, 2, 2, 2, 2, 2, 2, 1, -4}, 1},
+			ans{0},
+		},
+		question{
+			para{[]int{-1, 2, 2, 2, 2, 2, 2, 2, 1, -4}, 0},
+			ans{0},
+		},
 		// 如需多个测试，可以复制上方元素。
 	}
 

Algorithms/0016.3sum-closest/README.md

@@ -8,7 +8,7 @@ For example, given array S = {-1 2 1 -4}, and target = 1.
 The sum that is closest to the target is 2. (-1 + 2 + 1 = 2).
 ```
 ## 解题思路
-
+这一题和15题的思路基本一致。
 
 ## 总结