两个数之和
给定一个整数数组 nums
和一个目标值 target
,请你在该数组中找出和为目标值的那两个整数,并返回他们的下标。
// 解法1:此解法耗时多,占用的内存较少
func twoSum(_ nums: [Int], _ target: Int) -> [Int] {
var arr = [-1,-1]
for index1 in 0..<nums.count-1 {
for index2 in index1+1..<nums.count{
if (nums[index1] + nums[index2] == target) {
arr[0] = index1;
arr[1] = index2;
return arr;
}
}
}
return arr;
}
// 解法2:此解法耗时较少,但是占用的内存较大
func twoSum(_ nums: [Int], _ target: Int) -> [Int] {
var dict = Dictionary<Int,Int>()
for (index,value) in nums.enumerated() {
dict[value] = index
}
var arr = [-1,-1]
for (index,value) in nums.enumerated() {
if dict.keys.contains(target-value) && dict[target-value] != index{
arr[0] = index
arr[1] = dict[target-value] ?? -1
return arr;
}
}
return arr;
}