package offer;

/**

* @author ： CodeWater

* @create ：2022-03-10-13:56

* @Function Description ：剑指 Offer 04.

* 二维数组中的查找

*/

public class _4FindNumber {

//暴力

public boolean findNumberIn2DArray(int[][] matrix, int target) {

//可能为空

if (matrix == null || matrix.length == 0 || matrix[0].length == 0)

return false;

int rows = matrix.length, cols = matrix[0].length;

for (int i = 0; i < rows; i++) {

for (int j = 0; j < cols; j++) {

if (matrix[i][j] == target) return true;

}

}

return false;

}

public boolean findNumberIn2DArray2(int[][] matrix, int target) {

//方法二:从每一行的末尾开始判断

if (matrix == null || matrix.length == 0 || matrix[0].length == 0)

return false;

int rows = matrix.length, cols = matrix[0].length;

int row = 0, col = cols - 1;

while (row < rows && col >= 0) {

if (matrix[row][col] == target) return true;

else if (matrix[row][col] > target) col--;

else row++; //这一行的值小于target;往下一行找

}

return false;

}

}