1663-SmallestStringWithAGivenNumericValue.go

package main

// 1663. Smallest String With A Given Numeric Value
// The numeric value of a lowercase character is defined as its position (1-indexed) in the alphabet, 
// so the numeric value of a is 1, the numeric value of b is 2, the numeric value of c is 3, and so on.

// The numeric value of a string consisting of lowercase characters is defined as the sum of its characters' numeric values. 
// For example, the numeric value of the string "abe" is equal to 1 + 2 + 5 = 8.

// You are given two integers n and k. 
// Return the lexicographically smallest string with length equal to n and numeric value equal to k.

// Note that a string x is lexicographically smaller than string y if x comes before y in dictionary order, 
// that is, either x is a prefix of y, or if i is the first position such that x[i] != y[i], 
// then x[i] comes before y[i] in alphabetic order.

// Example 1:
// Input: n = 3, k = 27
// Output: "aay"
// Explanation: The numeric value of the string is 1 + 1 + 25 = 27, and it is the smallest string with such a value and length equal to 3.

// Example 2:
// Input: n = 5, k = 73
// Output: "aaszz"

// Constraints:
//     1 <= n <= 10^5
//     n <= k <= 26 * n

import "fmt"

func getSmallestString(n int, k int) string {
    res := []byte{}
    for i := 0; i < n; i++ { // 生成 n 个 a
        res = append(res, 'a')
        k--
    }
    min := func (x, y int) int { if x < y { return x; }; return y; }
    for i := n - 1; i >= 0; i-- {
        res[i] += byte(min(25, k)) // 优先替换的 z
        k -= min(25, k)
    }
    return string(res)
}

func main() {
    // Example 1:
    // Input: n = 3, k = 27
    // Output: "aay"
    // Explanation: The numeric value of the string is 1 + 1 + 25 = 27, and it is the smallest string with such a value and length equal to 3.
    fmt.Println(getSmallestString(3, 27)) // "aay"
    // Example 2:
    // Input: n = 5, k = 73
    // Output: "aaszz"
    fmt.Println(getSmallestString(5, 73)) // "aaszz"
}