556. The next larger element III

Original link ：556. Next bigger element III

 

solution:

         

class Solution {
public:
    int nextGreaterElement(int n) {
        string s = to_string(n);    // Process numeric programming strings 
        int k = s.size() - 1;
        while(k > 0 && s[k - 1] >= s[k]) k--;   // From back to front, if it is in ascending order, it is the largest number 
        if(!k) return -1;   // If the whole string is in ascending order from back to front , Nothing is bigger than it 
        int t = k;
        while(t + 1 < s.size() && s[t + 1] > s[k - 1]) t++; // from k + 1 Start , Find the first match s[k - 1] Big numbers 
        swap(s[k - 1], s[t]);
        reverse(s.begin() + k,s.end());
        long long res = stoll(s);
        if(res > INT_MAX) return -1;
        return res;
    }
};