54. Spiral Matrix

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LeetCode

59. Spiral Matrix II

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class Solution {
    public List<Integer> spiralOrder(int[][] matrix) {
        List<Integer> res=new ArrayList<>();
        if(matrix.length==0) return res;

        int matrixSize=matrix.length*matrix[0].length;
        int left=-1,right=matrix[0].length-1;
        int top=0,down=matrix.length-1;

        while(left<=right){
            for(int i=++left;i<=right;i++){
                if(res.size()==matrixSize) return res;
                res.add(matrix[top][i]);
            }
            for(int i=++top;i<=down;i++){
                if(res.size()==matrixSize) return res;
                res.add(matrix[i][right]);
            }
            for(int i=--right;i>=left;i--){
                if(res.size()==matrixSize) return res;
                res.add(matrix[down][i]);
            }
            for(int i=--down;i>=top;i--){
                if(res.size()==matrixSize) return res;
                res.add(matrix[i][left]);
            }
        }

        return res;
    }
}
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class Solution {
    public List < Integer > spiralOrder(int[][] matrix) {
        List ans = new ArrayList();
        if (matrix.length == 0)
            return ans;
        int top = 0, down = matrix.length - 1;
        int left = 0, right = matrix[0].length - 1;
        while (top <= down && left <= right) {
            for (int i = left; i <= right; i++) ans.add(matrix[top][i]);
            for (int i = top + 1; i <= down; i++) ans.add(matrix[i][right]);
            if (top < down && left < right) {
                for (int i = right - 1; i > left; i--) ans.add(matrix[down][i]);
                for (int i = down; i > top; i--) ans.add(matrix[i][left]);
            }
            top++;
            down--;
            left++;
            right--;
        }
        return ans;
    }
}
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