java常用算法

冒泡排序：

    //降序
    public static int[] bubbleSort(int[] array){
        for(int i = 0; i < array.length; i++){
            int curval = array[i];
            for(int j = i - 1; j >= 0; j--){
                int temp = array[j];
                if(curval > temp){
                    array[j] = curval;
                    array[j+1] = temp;
                }
            }
        }
        return array;
    }

    //升序
    public static int[] bubbleSort(int[] array){
        for(int i = array.length - 1; i >= 0; i--){
            int curval = array[i];
            for(int j = i; j < array.length-1; j++){
                int tempval = array[j+1];
                if(tempval < curval){
                    array[j+1] = curval;
                    array[j] = tempval;
                }
            }
        }
        return array;
    }

二分法查找

//降序
    public static int binarySearch (int[] array, int search){
        int start = 0;
        int end = array.length-1;
        int middle = array.length / 2;
        for(; start <= end; ){
            middle = (start + end) / 2;
            int val = array[middle];
            if(val == search){
                return middle;
            }else if(val > search){
                start = middle + 1;
            }else{
                end = middle - 1;
            }
        }

        return -1;

    }

　　//升序
    public static int binarySearch(int[] array, int search){
        int start = 0;
        int end = array.length - 1;
        int middle = (start + end) / 2;
        for(;start <= end;){
            middle = (start + end) / 2;
            int midval = array[middle];
            if(midval > search){
                end = middle - 1;
            }else if(midval < search){
                start = middle + 1;
            }else{
                return middle;
            }
        }
        return -1;
    }

调用

    public static void main(String[] args){
        int[] test = new int[]{1,200,164,29,298,188,34,52,287,100,33};
        int[] bubres = bubbleSort(test);
        for(int i = 0; i < bubres.length; i++){
            System.out.println(i + "*************" + bubres[i]);
        }

        System.out.println("-----*****" + binarySearch(bubres, 1));
    }