41. 缺失的第一个正数

https://leetcode-cn.com/problems/first-missing-positive/submissions/

func firstMissingPositive(_ nums: [Int]) -> Int {
    var NumArr = nums
    
    for idx in stride(from: 0, to: NumArr.count, by: 1) {
        while ((NumArr[idx] >= 1 && NumArr[idx] <= NumArr.count) && (NumArr[idx] != NumArr[NumArr[idx] - 1])) {
            let tmp = NumArr[idx]
            NumArr[idx] = NumArr[tmp - 1]
            NumArr[tmp - 1] = tmp
        }
    }
    
    var result = NumArr.count + 1
    for (idx, item) in NumArr.enumerated() {
        if item != idx + 1 {
            result = idx + 1
            break
        }
    }
    return result
}