JavaProgramming/SpiralMatrix.java at main · Utkarsh-Raj-Profile/JavaProgramming · GitHub

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public class SpiralMatrix {
    public static void printspiral(int matrix[] [] ) {
        int startrow =0;
        int startcol =0;
        int endrow =matrix.length-1;
        int endcol =matrix[0].length-1;

        while (startrow <= endrow && startcol <= endcol) {
            //top boundry
            for(int j=startcol;j<=endcol;j++){
                System.out.print(matrix[startrow][j] + " ");
            }

            //right boundry
            for(int i=startrow + 1;i<=endrow;i++){
                System.out.print(matrix[i][endcol] + " ");
            }

            //bouttom boundry
            for(int j=endcol-1;j>=startcol;j--){
                if (startrow == endrow) {
                    break;
                }
                System.out.print(matrix[endrow][j] + " ");
            }

            //left boundry
            for(int i=endrow-1;i>=startrow+1;i--){
                if (startcol == endcol) {
                    break;
                }
                System.out.print(matrix[i][startcol] + " ");
            }

            startcol++;
            startrow++;
            endcol--;
            endrow--;
        }
        System.out.println();

    }
    public static int diagonalsum(int matrix[][]) {
        int sum =0;

        // -- brut force      // O(n^2) -- Time Complexity

        // for(int i = 0; i<matrix.length;i++){
        //     for(int j=0; j<matrix[0].length;j++){
        //         if (i == j) {
        //             sum += matrix[i][j];
        //         }
        //         else if (i+j == matrix.length-1) {
        //             sum += matrix[i][j];
        //         }
        //     }
        // }

        for(int i=0;i<matrix.length;i++){              //O(n)      -- Time Complixity
            //pd
            sum += matrix[i][i];
            //sd
            if (i != matrix.length-1-i) {
                sum += matrix[i][matrix.length-i-1];
            }
        }
        return sum;
    }
    public static void main(String[] args) {
        int matrix[][] = {{1,2,3,4},
                         {5,6,7,8},
                         {9,10,11,12},
                         {13,14,15,16}};
        //printspiral(matrix);
        System.out.println(diagonalsum(matrix));
    }
}