Medium
You are given a string s
that consists of only digits.
Check if we can split s
into two or more non-empty substrings such that the numerical values of the substrings are in descending order and the difference between numerical values of every two adjacent substrings is equal to 1
.
s = "0090089"
can be split into ["0090", "089"]
with numerical values [90,89]
. The values are in descending order and adjacent values differ by 1
, so this way is valid.s = "001"
can be split into ["0", "01"]
, ["00", "1"]
, or ["0", "0", "1"]
. However all the ways are invalid because they have numerical values [0,1]
, [0,1]
, and [0,0,1]
respectively, all of which are not in descending order.Return true
if it is possible to split s
as described above__, or false
otherwise.
A substring is a contiguous sequence of characters in a string.
Example 1:
Input: s = “1234”
Output: false
Explanation: There is no valid way to split s.
Example 2:
Input: s = “050043”
Output: true
Explanation: s can be split into [“05”, “004”, “3”] with numerical values [5,4,3]. The values are in descending order with adjacent values differing by 1.
Example 3:
Input: s = “9080701”
Output: false
Explanation: There is no valid way to split s.
Constraints:
1 <= s.length <= 20
s
only consists of digits.public class Solution {
public boolean splitString(String s) {
return solve(0, -1, s, 0);
}
private boolean solve(int i, long prev, String s, int k) {
if (i == s.length()) {
return k >= 2;
}
long cur = 0;
for (int j = i; j < s.length(); j++) {
cur = cur * 10 + s.charAt(j) - '0';
if ((prev == -1 || prev - cur == 1) && solve(j + 1, cur, s, k + 1)) {
return true;
}
}
return false;
}
}