LeetCode-in-Java
1849. Splitting a String Into Descending Consecutive Values
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.
- For example, the string
s = "0090089"can be split into["0090", "089"]with numerical values[90,89]. The values are in descending order and adjacent values differ by1, so this way is valid. - Another example, the string
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 <= 20sonly consists of digits.
Solution
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;
}
}