算法題目---------------03轉圈打印矩陣（切割矩形），正方形旋轉90度，之字型打印矩陣，行和列都排好序找數

給定左上角和右下角座標，將矩陣切割成一個個小矩形，依次遍歷輸出，注意有可能e同行或同列的情況

public static void spiralOrderPrint(int[][] matrix) {
		int tR = 0;
		int tC = 0;
		int dR = matrix.length - 1;
		int dC = matrix[0].length - 1;
		while (tR <= dR && tC <= dC) {
			printEdge(matrix, tR++, tC++, dR--, dC--);
		}
	}

/**
*tR  左上角行
*tC  左上角列
*dR  右下角行
*dC  右下角列
*/
	public static void printEdge(int[][] m, int tR, int tC, int dR, int dC) {
		if (tR == dR) {//同行，則從左到右輸出
			for (int i = tC; i <= dC; i++) {
				System.out.print(m[tR][i] + " ");
			}
		} else if (tC == dC) {//同列，則從上到下輸出
			for (int i = tR; i <= dR; i++) {
				System.out.print(m[i][tC] + " ");
			}
		} else {//若構成一個矩形
			int curC = tC;
			int curR = tR;
			while (curC != dC) {
				System.out.print(m[tR][curC] + " ");
				curC++;
			}
			while (curR != dR) {
				System.out.print(m[curR][dC] + " ");
				curR++;
			}
			while (curC != tC) {
				System.out.print(m[dR][curC] + " ");
				curC--;
			}
			while (curR != tR) {
				System.out.print(m[curR][tC] + " ");
				curR--;
			}
		}
	}

 

正方形旋轉也是同上思路，不過要扣邊界

public static void rotate(int[][] matrix) {
		int tR = 0;
		int tC = 0;
		int dR = matrix.length - 1;
		int dC = matrix[0].length - 1;
		while (tR < dR) {
			rotateEdge(matrix, tR++, tC++, dR--, dC--);
		}
	}

	public static void rotateEdge(int[][] m, int tR, int tC, int dR, int dC) {
		int times = dC - tC; 
		int tmp = 0;
		for (int i = 0; i != times; i++) {
			tmp = m[tR][tC + i];
			m[tR][tC + i] = m[dR - i][tC];
			m[dR - i][tC] = m[dR][dC - i];
			m[dR][dC - i] = m[tR + i][dC];
			m[tR + i][dC] = tmp;
		}
	}

	public static void printMatrixZigZag(int[][] matrix) {
		int tR = 0;
		int tC = 0;
		int dR = 0;
		int dC = 0;
		int endR = matrix.length - 1;
		int endC = matrix[0].length - 1;
		boolean fromUp = false;
		while (tR != endR + 1) {
			printLevel(matrix, tR, tC, dR, dC, fromUp);
			tR = tC == endC ? tR + 1 : tR;
			tC = tC == endC ? tC : tC + 1;
			dC = dR == endR ? dC + 1 : dC;
			dR = dR == endR ? dR : dR + 1;
			fromUp = !fromUp;
		}
		System.out.println();
	}

	public static void printLevel(int[][] m, int tR, int tC, int dR, int dC,
			boolean f) {
		if (f) {
			while (tR != dR + 1) {
				System.out.print(m[tR++][tC--] + " ");
			}
		} else {
			while (dR != tR - 1) {
				System.out.print(m[dR--][dC++] + " ");
			}
		}
	}

	public static void main(String[] args) {
		int[][] matrix = { { 1, 2, 3, 4 }, { 5, 6, 7, 8 }, { 9, 10, 11, 12 } };
		printMatrixZigZag(matrix);

	}

最經典的就是三目運算，將每個點與其他點聯繫起來

 

行和列排好序，要求時間O(N+M),空間O1