#N766. Toeplitz Matrix
problem link

#solution

class Solution {
    public boolean isToeplitzMatrix(int[][] matrix) {
        for(int i=0; i<matrix.length-1; i++){
            for(int j=0; j<matrix[i].length-1; j++){
                if(matrix[i][j]!=matrix[i+1][j+1]) return false;
            }
        }
        
        return true;
    }
}

#N908. Smallest Range I
problem link

#solution

class Solution {
    public int smallestRangeI(int[] nums, int k) {
        int max=nums[0], min=nums[0];
        for(int n:nums){
            max = Math.max(max, n);
            min = Math.min(min, n);
        }
        return Math.max(max-min-2*k, 0); 
    }
}

#N1385. Find the Distance Value Between Two Arrays
problem link

#solution

class Solution {
    public int findTheDistanceValue(int[] arr1, int[] arr2, int d) {
        int res=0, l=arr2.length;
        
        Arrays.sort(arr1); Arrays.sort(arr2);
        for(int n:arr1){
            int count=0, start=0, end=l-1;
            while(start<=end){
                int mid=(start+end)/2;
                if(Math.abs(arr2[mid]-n)<=d) {
                    count++;
                    break;
                }
                if(arr2[mid]>n+d) end=mid-1;
                if(arr2[mid]<n-d) start=mid+1;
                
            }
            if(count==0) res++;
        }
        
        return res;
    }
}

#N575. Distribute Candies
problem link

#solution

class Solution {
    public int distributeCandies(int[] candyType) {
        Set<Integer> set = new HashSet<>();
        
        for(int candy:candyType)
            set.add(candy);
        
        return Math.min(set.size(), candyType.length/2);
    }
}

#N1800. Maximum Ascending Subarray Sum
problem link

#solution

class Solution {
    public int maxAscendingSum(int[] nums) {
        List<Integer> sumlist = new ArrayList<>();
        int sum=0, i=0;
        
        for(; i<nums.length-1; i++){
            if(nums[i]<nums[i+1]){
                sum+=nums[i];
            }else{
                sum+=nums[i];
                sumlist.add(sum);
                sum=0;
            }
        }
        sum+=nums[i];
        sumlist.add(sum);
        
        int max=sumlist.get(0);
        for(int n:sumlist)
            max=Math.max(max, n);
        
        return max;
    }
}

#N1582. Special Positions in a Binary Matrix
problem link

#solution

class Solution {
    public int numSpecial(int[][] mat) {
        int count=0, row[]=new int[mat.length], col[]=new int[mat[0].length];
        
        for(int i=0; i<mat.length; i++)
            for(int j=0; j<mat[i].length; j++)
                if(mat[i][j]==1){
                    row[i]++;
                    col[j]++;
                }
        
        for(int i=0; i<mat.length; i++)
            for(int j=0; j<mat[i].length; j++)
                if(mat[i][j]==1 && row[i] == 1 && col [j] == 1)
                    count++;
        
        return count;
    }
}

#N1619. Mean of Array After Removing Some Elements
problem link

#solution

class Solution {
    public double trimMean(int[] arr) {
        Arrays.sort(arr);
        
        for(int i=0; i<arr.length/20; i++)
            arr[i]=arr[arr.length-i-1]=0;
        
        int sum=0;
        for(int n:arr)
            sum+=n;
        
        return (double)sum/(arr.length*9/10);
    }
}

#N1550. Three Consecutive Odds
problem link

#solution

class Solution {
    public boolean threeConsecutiveOdds(int[] arr) {
        for(int i=0; i<arr.length-2; i++)
            if(arr[i]*arr[i+1]*arr[i+2] % 2 == 1) return true;
        
        return false;
    }
}

#N1598. Crawler Log Folder
problem link

#solution

class Solution {
    public int minOperations(String[] logs) {
        int res = 0;
        for (String s : logs) {
            if (s.equals("../")) res = Math.max(0, --res);
            else if (s.equals("./")) continue;
            else res++;
        }
        return res;
    }
}

#N1394. Find Lucky Integer in an Array
problem link

#solution

class Solution {
    public int findLucky(int[] arr) {
        int[] count = new int[501];
        
        for(int i: arr)
            count[i]++;
        
        for(int i=count.length-1; i>=0; i--){
            if(i==0) return -1;
            if(count[i]==i) return i;
        }
        
        return -1;
    }
}

P.S.: another approach with HashMap‼️

        int res=-1;
        Map<Integer, Integer> map = new HashMap<>();
        
        for(int n: arr)
            map.put(n, map.getOrDefault(n, 0) +1);
        
        for(Map.Entry<Integer, Integer> entry: map.entrySet())
            if(entry.getKey() == entry.getValue()) res = Math.max(res, entry.getValue());
        
        return res;

#N1260. Shift 2D Grid
problem link

#solution

class Solution {
    public List<List<Integer>> shiftGrid(int[][] grid, int k) {
        List<List<Integer>> list = new ArrayList<>();
        int m=grid.length, n=grid[0].length;
        while(k-- > 0){
            int temp=grid[m-1][n-1];
            for(int i=m-1; i>=0; i--){
                for(int j=n-1; j>0; j--){
                    if(i==0 && j==0) break;
                    grid[i][j]=grid[i][j-1];
                }
                if(i>0) grid[i][0]=grid[i-1][n-1];
            }
            grid[0][0]=temp;
        }
        
        for(int i=0; i<m; i++){
            List<Integer> sublist = new ArrayList<>();
            for(int j=0; j<n; j++){
                sublist.add(grid[i][j]);
            }
            list.add(sublist);
        }
        
        return list;
    }
}

#N566. Reshape the Matrix
problem link

#solution

class Solution {
    public int[][] matrixReshape(int[][] mat, int r, int c) {
        int[][] res = new int[r][c];
        int m = mat.length, n = mat[0].length;
        if(r*c != m*n) return mat;
        for(int i=0; i<r*c; i++)
            res[i/c][i%c] = mat[i/n][i%n];
        
        return res;
    }
}

#N169. Majority Element
problem link

#solution

class Solution {
    public int majorityElement(int[] nums) {
        Arrays.sort(nums);
        return nums[nums.length/2];
    }
}

#medium

#N2079. Watering Plants
problem link

#solution

class Solution {
    public int wateringPlants(int[] plants, int capacity) {
        int steps=0, temp=capacity;
        for(int i=0; i<plants.length; i++){
            if(plants[i]<=temp){
                steps++;
                temp-=plants[i];
            }else{
                temp=capacity-plants[i];
                steps+=2*i+1;
            }
        }
        
        return steps;
    }
}

#N2022. Convert 1D Array Into 2D Array
problem link

#solution

class Solution {
    public int[][] construct2DArray(int[] original, int m, int n) {
        int[][] res = new int[m][n];
        if(m*n != original.length) return new int[0][0];
        
        for(int i=0; i<m*n; i++)
            res[i/n][i%n] = original[i];
        
        return res;
    }
}

#N867. Transpose Matrix
problem link

#solution

class Solution {
    public int[][] transpose(int[][] matrix) {
        int m = matrix.length, n = matrix[0].length;
        int[][] res = new int[n][m];
        
        for(int i=0; i<m*n; i++)
            res[i%n][i/n] = matrix[i/n][i%n];
        
        return res;
    }
}

#N1437. Check If All 1's Are at Least Length K Places Away
problem link

#solution

class Solution {
    public boolean kLengthApart(int[] nums, int k) {
        int temp=k;
        
        for(int i=0; i<nums.length; i++){
            if(nums[i]==1){
                if(temp<k) return false;
                temp=0;
            }else
                temp++;
        }
        
        return true;
    }
}