蓝桥杯练习第二天

题目1

代码：

package day2;

import java.util.Arrays;

public class day2_test1 {
    public static int search(int[] nums, int target) {
        Arrays.sort(nums);
        for(int i=0;i< nums.length;i++){
            if(nums[i] == target){
                return i;
            }
        }

        return -1;
    }

    public static void main(String[] args) {
        int[] nums ={-1,0,3,5,9,12};
        int target = 2;
        System.out.println(search(nums, target));
    }
}

运行截图：

题目2

代码：

package day2;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class day2_test2 {
    public static List<Integer> targetIndices(int[] nums, int target) {
        List<Integer> result = new ArrayList<>();
        Arrays.sort(nums);
        for (int i = 0; i < nums.length; i++) {
            if(nums[i] == target){
                result.add(i);
            }
        }
        return result;
    }

    public static void main(String[] args) {
        int[] nums = {1,2,5,2,3};
        List<Integer> li1 = targetIndices(nums,4);
        List<Integer> li2 = targetIndices(nums,5);
        List<Integer> li3 = targetIndices(nums,3);
        List<Integer> li4 = targetIndices(nums,2);
        System.out.println(li1);
        System.out.println(li2);
        System.out.println(li3);
        System.out.println(li4);
    }
}

运行截图：

题目3

代码：

package day2;

import java.util.HashMap;

public class day2_test3 {
    public static int findDuplicate(int[] nums) {
        int result =0;
        for(int i=0; i< nums.length; i++){
            for(int j =0; j< nums.length;j++){
                if(i == j){
                    continue;
                }
                if(nums[i] == nums[j]){
                    result = nums[i];
                }
            }
        }
        return result;
    }

    public static void main(String[] args) {
        int[] nums = {1,3,4,2,2};
        int[] nums1 = {3,1,3,4,2};
        System.out.println(findDuplicate(nums));
        System.out.println(findDuplicate(nums1));
    }
}

运行截图：

题目4

代码：

package day2;

import java.util.ArrayList;

public class day_test4 {

//    左 = 右: index += 1
//    左 > 右:删除get(0),index = 0
//    右 > 左:删除get(array.size() - 1),index = 0
    public static int solute(int s, int[] nums){
        int result = 0;
        int sum = 0;
        int index = 0;

        ArrayList<Integer> array = new ArrayList<>();
        for(int i=0; i< nums.length; i++){
            array.add(nums[i]);
        }
        while(!(sum == s)){
            sum = 0;
            for(int num:array){
                sum += num;
            }

            if(sum < s){
                return -1;
            }
                if(array.get(index) == array.get(array.size() - 1 -index)){
                   index += 1;
                    continue;
                } else if (array.get(index) > array.get(array.size() - 1 -index)){
                    array.remove(0);
                    result += 1;
                    index = 0;
                } else if (array.get(index) < array.get(array.size() - 1 -index)) {
                    array.remove(array.size() - 1);
                    result += 1;
                    index = 0;

                }
        }
        return result;
    }

    public static void main(String[] args) {
        int[] nums = {0,1,0,1,1,1,0,0,1};
        int[] nums1 = {1,1,0,0,1,0,0,1,1,0,0,0,0,0,1,1};
        System.out.println(solute(3,nums));
        System.out.println(solute(2,nums1));
    }
}

运行截图：