数据结构与算法之“之”字型打印矩阵和矩阵中找数

墨蓝 2022-01-07 10:23 215阅读 0赞

# 数据结构与算法之“之”字型打印矩阵和矩阵中找数 #

--------------------

## 目录 ##

1.  “之”字型打印矩阵
2.  在行列都排好序的矩阵中找数

--------------------

### 1. “之”字型打印矩阵 ###

1.  题目描述  
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MTkxMDY5NA_size_16_color_FFFFFF_t_70]
2.  思路：创建A，B两个点，A往右移，B往下移，当移到最右边和最下边则向下移和右移。AB两点连线即为打印路径，添加个flag判断从下打印还是从上打印即可。

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MTkxMDY5NA_size_16_color_FFFFFF_t_70 1]

1.  代码实现

public class Code_ZigZagPrintMatrix {
        
    
        public static void printMatrixZigZag(int[][] matrix) {
        
            int aR = 0;
            int aC = 0;
            int bR = 0;
            int bC = 0;
            int endR = matrix.length - 1;
            int endC = matrix[0].length - 1;
            boolean fromUp = false;
            while (aR != endR + 1) {
        
                printLevel(matrix, aR, aC, bR, bC, fromUp);
                aR = aC == endC ? aR + 1 : aR;
                aC = aC == endC ? aC : aC + 1;
                bC = bR == endR ? bC + 1 : bC;
                bR = bR == endR ? bR : bR + 1;
                fromUp = !fromUp;
            }
            System.out.println();
        }
    
        public static void printLevel(int[][] m, int aR, int aC, int bR, int bC,
                                      boolean f) {
        
            if (f) {
        
                while (aR != bR + 1) {
        
                    System.out.print(m[aR++][aC--] + " ");
                }
            } else {
        
                while (bR != aR - 1) {
        
                    System.out.print(m[bR--][bC++] + " ");
                }
            }
        }
    
        public static void main(String[] args) {
        
            int[][] matrix = {
         {
         1, 2, 3, 4 }, {
         5, 6, 7, 8 }, {
         9, 10, 11, 12 } };
            printMatrixZigZag(matrix);
        }
    }

1.  编译结果  
    ![在这里插入图片描述][20190627095933854.png]

--------------------

### 在行列都排好序的矩阵中找数 ###

1.  题目描述  
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MTkxMDY5NA_size_16_color_FFFFFF_t_70 2]
2.  思路：从右上角出去，当找的数比当前数大时，则向下走，如果找的数比当前数小数则向左走，没找到就返回false。

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MTkxMDY5NA_size_16_color_FFFFFF_t_70 3]

1.  代码实现

public class Code_FindNumInSortedMatrix {
        
    
    	public static boolean isContains(int[][] matrix, int K) {
        
    		int row = 0;
    		int col = matrix[0].length - 1;
    		while (row < matrix.length && col > -1) {
        
    			if (matrix[row][col] == K) {
        
    				return true;
    			} else if (matrix[row][col] > K) {
        
    				col--;
    			} else {
        
    				row++;
    			}
    		}
    		return false;
    	}
    
    	public static void main(String[] args) {
        
    		int[][] matrix = new int[][] {
         {
         0, 1, 2, 3, 4, 5, 6 },// 0
    				{
         10, 12, 13, 15, 16, 17, 18 },// 1
    				{
         23, 24, 25, 26, 27, 28, 29 },// 2
    				{
         44, 45, 46, 47, 48, 49, 50 },// 3
    				{
         65, 66, 67, 68, 69, 70, 71 },// 4
    				{
         96, 97, 98, 99, 100, 111, 122 },// 5
    				{
         166, 176, 186, 187, 190, 195, 200 },// 6
    				{
         233, 243, 321, 341, 356, 370, 380 } // 7
    		};
    		int K = 233;
    		System.out.println(isContains(matrix, K));
    	}
    
    }

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MTkxMDY5NA_size_16_color_FFFFFF_t_70]: /images/20211223/2cbeed69f2934adb8e596ea9733a59f2.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MTkxMDY5NA_size_16_color_FFFFFF_t_70 1]: /images/20211223/e029af48fe1a4762b3d0f127d8e80eb2.png
[20190627095933854.png]: /images/20211223/249d91012e4f4ec482cd18db02dfb3ea.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MTkxMDY5NA_size_16_color_FFFFFF_t_70 2]: /images/20211223/978782e2bd7c4fa385d639e2f31652b3.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MTkxMDY5NA_size_16_color_FFFFFF_t_70 3]: /images/20211223/39c465ad31f44b8a9ad4561e2887219b.png