Formatted question description: https://leetcode.ca/all/556.html
556. Next Greater Element III (Medium)
Given a positive 32-bit integer n, you need to find the smallest 32-bit integer which has exactly the same digits existing in the integer n and is greater in value than n. If no such positive 32-bit integer exists, you need to return -1.
Example 1:
Input: 12 Output: 21
Example 2:
Input: 21 Output: -1
Related Topics:
String
Similar Questions:
Solution 1.
// OJ: https://leetcode.com/problems/next-greater-element-iii/
// Time: O(1)
// Space: O(1)
class Solution {
public:
int nextGreaterElement(int n) {
auto s = to_string(n);
for (int i = s.size() - 2; i >= 0; --i) {
if (s[i] >= s[i + 1]) continue;
int j = lower_bound(s.begin() + i + 1, s.end(), s[i], greater<int>()) - s.begin() - 1;
swap(s[i], s[j]);
sort(s.begin() + i + 1, s.end());
long n = stol(s);
return n > INT_MAX ? -1 : n;
}
return -1;
}
};
Solution 2.
// OJ: https://leetcode.com/problems/next-greater-element-iii
// Time: O(1)
// Space: O(1)
// Ref: https://discuss.leetcode.com/topic/85740/c-4-lines-next_permutation
class Solution {
public:
int nextGreaterElement(int n) {
auto digits = to_string(n);
next_permutation(begin(digits), end(digits));
auto ans = stol(digits);
return (ans > INT_MAX || ans <= n) ? -1 : ans;
}
};
Java
class Solution {
public int nextGreaterElement(int n) {
char[] array = String.valueOf(n).toCharArray();
boolean next = nextPermutation(array);
if (!next)
return -1;
String nextGreaterElementStr = new String(array);
long nextGreaterElementLong = Long.parseLong(nextGreaterElementStr);
if (nextGreaterElementLong > Integer.MAX_VALUE)
return -1;
else {
int nextGreaterElement = (int) nextGreaterElementLong;
return nextGreaterElement;
}
}
public boolean nextPermutation(char[] array) {
int length = array.length;
int index = -1;
char curChar = Character.MAX_VALUE;
for (int i = length - 1; i > 0; i--) {
int difference = array[i] - array[i - 1];
if (difference > 0) {
index = i - 1;
curChar = array[i - 1];
break;
}
}
if (index < 0) {
Arrays.sort(array);
return false;
}
int nextIndex = -1;
char nextChar = Character.MAX_VALUE;
for (int i = index + 1; i < length; i++) {
if (array[i] > curChar && array[i] < nextChar) {
nextIndex = i;
nextChar = array[i];
}
}
array[index] = nextChar;
array[nextIndex] = curChar;
Arrays.sort(array, index + 1, length);
return true;
}
}