[670. Maximum Swap] #leetcode

670_0902.java

class Solution {
    public int maximumSwap(int num) {
        String temp = Integer.toString(num);
        int[] nums = new int[temp.length()];
        for (int i = 0; i < temp.length(); i++) nums[i] = temp.charAt(i) - '0';
        
        boolean flag = false;
        List<Integer> maxIdx = new ArrayList<Integer>();
        for (int i = 0; i < nums.length-1; i++) {
            int max=0;
            for (int j = i+1; j < nums.length; j++) {
                if (nums[j] > nums[i]) {
                    if (nums[j] > max) {
                        max = nums[j];
                        maxIdx = new ArrayList<Integer>();
                        maxIdx.add(j);
                    } else if (nums[j] == max) {
                        maxIdx.add(j);
                    }
                } 
            }
            
            if (max != 0) {
                int res = 0;
                StringBuilder strNum;
                for (Integer idx : maxIdx) {
                    nums[idx] = nums[i];
                    nums[i] = max;
                    strNum = new StringBuilder();
                    for (int n : nums) strNum.append(n);
                    res = Math.max(res, Integer.parseInt(strNum.toString()));
                    
                    nums[i] = nums[idx];
                    nums[idx] = max;
                }
                return res;
            }
        }
        return num;
    }
}