[leetcode] Spiral Matrix | 把一个2D matrix用螺旋方式打印

Posted by: lexigrey on: November 23, 2013

• In: leetcode
• 5 Comments

遇见这种matrix题就腿发软，bf给讲了个四条边bound的方法，立刻15分钟bug free了。高兴够呛。

public int[][] generateMatrix(int n) {
    int[][] res = new int[n][n];
    int k = 1;
    int top = 0, bottom = n - 1, left = 0, right = n - 1;
    while (left < right && top < bottom) {
        for (int j = left; j < right; j++) {
            res[top][j] = k++;
        }
        for (int i = top; i < bottom; i++) {
            res[i][right] = k++;
        }
        for (int j = right; j > left; j--) {
            res[bottom][j] = k++;
        }
        for (int i = bottom; i > top; i--) {
            res[i][left] = k++;
        }
        left++;
        right--;
        top++;
        bottom--;
    }
    if (n % 2 != 0)
        res[n / 2][n / 2] = k;
    return res;
}

Tags: matrix