LeetCodeの912題配列ソートをテストとし,結果が小さいものから大きいものへのソートが要求される.

バブルソート

class Solution {
    public int[] sortArray(int[] nums) {
		for(int i=0; i<nums.length; i++){
			for(int j=0; j<nums.length-i-1; j++){
				if(nums[j] > nums[j+1]){
					int temp = nums[j];
        			nums[j] = nums[j+1];
        			nums[j+1] = temp;
        		}
			}
		} 
		return nums;
    }
}

ソートの選択

class Solution {
    public int[] sortArray(int[] nums) {
        int minIndex,temp;
        for(int i=0; i<nums.length; i++){
            minIndex = i;
			for(int j=i+1; j<nums.length; j++){
				if(nums[j] < nums[minIndex])
                    minIndex = j;					
			}
            temp = nums[i];
        	nums[i] = nums[minIndex];
        	nums[minIndex] = temp;
		} 
		return nums;
    }
}

クイックソート

class Solution {
	public int[] sortArray(int[] nums) {
		return sort(nums,0,nums.length-1);
	}
    private int[] sort(int[] nums, int low,int high){
        int k = partition(nums,low,high);
        if(k>low) sort(nums,low,k-1);
        if(k<high) sort(nums,k+1,high);
        return nums;
    }

    private int partition(int nums[], int low,int high){
        int point = nums[low];
        while(low < high){
            while(low < high && nums[high] >= point)
                high--;
            swap(nums,low,high);
            while(low < high && nums[low] <= point)
                low++;
            swap(nums,low,high);
        }
        return low;
    }

    private void swap(int[] nums,int low,int high){
        int temp = nums[low];
        nums[low] = nums[high];
        nums[high] = temp;
    }
}