字符串 最长公共前缀

LC 最长公共前缀

编写一个函数来查找字符串数组中的最长公共前缀。

如果不存在公共前缀，返回空字符串 “”。

输入：strs = [“flower”,“flow”,“flight”]
输出：“fl”

swift 实现

class ViewController: UIViewController {
    

    override func viewDidLoad() {
    
        super.viewDidLoad()
        // Do any additional setup after loading the view.
        
        let strs = ["flower","flow","flight"]
        //let strs = ["dog","racecar","car"]
        //let strs = ["ab", "a"]
        //let strs = ["flower","flower","flower","flower"]
        print(longestCommonPrefix(strs))
    }
    
    func longestCommonPrefix(_ strs: [String]) -> String {
    
        
        if strs.count == 0 {
    
            return ""
        }

        if strs.count == 1 {
    
            return strs[0]
        }
        
        // 按第一个字符串进行遍历

        let array = Array(strs[0])
        
        for i in 0..<array.count {
    
            
            let c = array[i]
            
            var index = 1
            while index < strs.count {
    
                
                let temp = Array(strs[index])
                
                if temp.count > i {
    
                
                    if c != temp[i] {
    
                        
                        if i > 0 {
    
                            return String(strs[0].prefix(i))
                        }
                        else {
    
                            return ""
                        }
                    }
                }
                else {
    
                    return String(strs[0].prefix(i))
                }
                
                index += 1
            }
        }
        
        return strs[0]
    }
}

思路：