Matrix Array

Matrix Array旋转，输入flag 0 往左转，flag 1往右转
EX:{{1,2,3}, {4,5,6}} 1, return {{4,1}, {5,2}, {6,3}}
{{1,2,3}, {4,5,6}} 0, return {{3,6}, {2,5}, {1,4}}
基本双层Loop 下标变换一下搞定
leetcode 上就48，74，240算是有点相似，但也只是打基础，要会。

public static int[][] Solution(int[][] matrix, int flag) {
        if (matrix == null || matrix.length == 0 || matrix[0].length == 0)  return matrix;
        //int m = matrix.length, n = matrix[0].length;
        int[][] rvalue;
        rvalue = transpose(matrix);
        flip(rvalue, flag);
        return rvalue;
    }

    private static int[][] transpose(int[][] matrix) {
        int m = matrix.length, n = matrix[0].length;
        int[][] rvalue = new int[n][m];
        for (int i = 0; i < n; i++)
            for (int j = 0; j < m; j++)
                rvalue[i][j] = matrix[j][i];
        return rvalue;
    }

    private static void flip(int[][] matrix, int flag) {
        int m = matrix.length, n = matrix[0].length;
        if (flag == 1) {    //clock wise
            for (int i = 0; i < m; i++)
                for (int j = 0; j < n / 2; j++) {
                    int temp=matrix[i][j];
                    matrix[i][j]=matrix[i][n-j-1];
                    matrix[i][n-j-1]=temp;
                }
        }
        else {
            for (int i = 0; i < m / 2; i++)
                for (int j = 0; j < n; j++) {
                    int tmep= matrix[i][j];
                     matrix[i][j]=matrix[m-i-1][j];
                     matrix[m-i-1][j]=tmep;
                }
        }
    }

74. Search a 2D Matrix

public class Solution {
    public boolean searchMatrix(int[][] matrix, int target) {
        int row=matrix.length;
        int col=matrix[0].length;
        int start=0,end=row*col-1;
        while(start<=end){
            int mid=(start+end)/2;
            int mid_value=matrix[mid/col][mid%col];
            if(mid_value==target) return true;
            else if(mid_value>target) end=mid-1;
            else start=mid+1;
        }
        return false;
    }
}

240. Search a 2D Matrix II

public class Solution {
    public boolean searchMatrix(int[][] matrix, int target) {
        int row=0,col=matrix[0].length-1;
        while(row<=matrix.length-1&&col>=0){
            if(target==matrix[row][col]){
                return true;
            }else if(target>matrix[row][col]){
                row++;
            }else{
                col--;
            }
        }
        return false;
    }
}