题目描述

代码实现

import UIKit

func strStr(_ haystack: String, _ needle: String) -> Int {
    
    var stack : String = haystack
    
    if needle.isEmpty {
        return 0
    } else if !haystack.contains(needle) {
        return -1
    } else {
        var cnt = 0
        while !stack.hasPrefix(needle) {
            cnt = cnt + 1
            stack.removeFirst()
        }
        return cnt
    }
}

var haystack = " "
var needle = " "

strStr(haystack, needle)

Q.E.D.