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 <= 105n <= k <= 26 * n
答案
func getSmallestString(n int, k int) string {
res := make([]rune, 0,n)
smallest := 'a'
check := func(e rune, len, k int) bool {
e = e- 'a' + 1
if 26*(len-1) < k-int(e) || len-1 > k-int(e) {
return false
}
return true
}
for n > 0 {
//检查smallest是否满足
if check(smallest, n, k) {
res = append(res, smallest)
n--
k -= int(smallest-'a'+1)
} else {
smallest++
}
}
return string(res)
}
