문제

https://leetcode.com/problems/sign-of-the-product-of-an-array/

https://leetcode.com/problems/toeplitz-matrix/

https://leetcode.com/problems/divisor-game/

https://leetcode.com/problems/number-of-students-unable-to-eat-lunch/

https://leetcode.com/problems/island-perimeter/

https://leetcode.com/problems/find-nearest-point-that-has-the-same-x-or-y-coordinate/

https://leetcode.com/problems/unique-email-addresses/

https://leetcode.com/problems/next-greater-element-i/

토펠츠 문제 v1

https://leetcode.com/problems/toeplitz-matrix/

public boolean isToeplitzMatrix(int[][] matrix) {

        List<Dot> dots = new ArrayList<>();

        for(int i=0 ; i<matrix.length ; i++) {
            for(int j=0 ; j<matrix[i].length ; j++) {
                dots.add(new Dot(i, j, matrix[i][j]));
            }
        }

        //yMinX 가 같은수끼리 벨류가 같은지 검증하고  하나라도 틀리면 실패
        int difEnd = Math.min(matrix.length,matrix[0].length)-1;//단축길이 -1
        int difStart = Math.max(matrix.length,matrix[0].length)-2;//장축길이 -2

        int dif = difStart;
        int validator = -1;

        while (dif != difEnd ) {
            for(int i=0 ; i<dots.size() ; i++) {
                Dot dot = dots.get(i);
                if(dot.yMinX == dif) {

                    if(validator == -1) {
                        validator = dot.value;
                    }
                    else {
                        if(validator != dot.value) {
                            return false;
                        }
                    }
                }
            }
            dif++;

        }

        return true;
    }
    class Dot {
        int yMinX;
        int y;
        int x;
        int value;

        public Dot(int y, int x,int value) {
            this.y = y;
            this.x = x;
            this.value = value;
            this.yMinX = this.y - this.x;

        }
    }

토펠츠 v2