BAEKJOON 2679 - The Next Permutation

문제: https://www.acmicpc.net/problem/2697

문제

For this problem, you will write a program that takes a (possibly long) string of decimal digits, and outputs the permutation of those decimal digits that has the next larger value (as a decimal number) than the input number. For example: 

123 -> 132
279134399742 -> 279134423799

It is possible that no permutation of the input digits has a larger value. For example, 987.

입력

The first line of input contains a single integer P, (1 ≤ P ≤ 1000), which is the number of data sets that follow. Each data set is a single line that contains the data set number, followed by a space, followed by up to 80 decimal digits which is the input value.

출력

For each data set there is one line of output. If there is no larger permutation of the input digits, the output should be the data set number followed by a single space, followed by the string BIGGEST. If there is a solution, the output should be the data set number, a single space and the next larger permutation of the input digits.

예제 입력 

3
123
279134399742
987

예제 출력 

132
279134423799
BIGGEST

힌트

출처

ACM-ICPC > Regionals > North America > Greater New York Region > 2009 Greater New York Programming Contest E번

뒷자리의 숫자부터 검색하여 바꿀 수 있는 숫자가 있는지 찾는 방법으로 풀었봤습니다.

#include <fstream>
#include <iostream>
#include <cstring>
#include <climits>
#include <algorithm>
 
#include <string>
#include <set>
using namespace std;
 
int main()
{
    int cases;
    cin >> cases;
    for (int c = 0; c < cases; c++)
    {
        string str, strNum;
        cin >> str;
        strNum = str;
        int largest = strNum[strNum.size() - 1] - '0';
        multiset<int> numbers;
        numbers.clear();
        numbers.insert(largest);
        for (int i = strNum.size() - 2; i >= 0; i--)
        {
            if (strNum[i] - '0' < largest)
            {
                int replaceNumber;
                for (auto& num : numbers)
                {
                    if (num > strNum[i] - '0')
                    {
                        replaceNumber = num;
                        break;
                    }
                }
                multiset<int>::iterator it = numbers.find(replaceNumber);
                numbers.erase(it);
                numbers.insert(strNum[i] - '0');
                strNum[i] = replaceNumber + '0';
                int j = i + 1;
                for (auto& num : numbers)
                {
                    strNum[j] = num + '0';
                    j++;
                }
                break;
            }
            else if (largest < strNum[i] - '0')
            {
                largest = strNum[i] - '0';
            }
            numbers.insert(strNum[i] - '0');
        }
        if (str == strNum)
            cout << "BIGGEST" << endl;
        else
            cout << strNum << endl;
    }
 
    return 0;
}