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41 lines
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41 lines
2.3 KiB
HTML
<p>There is a city composed of <code>n x n</code> blocks, where each block contains a single building shaped like a vertical square prism. You are given a <strong>0-indexed</strong> <code>n x n</code> integer matrix <code>grid</code> where <code>grid[r][c]</code> represents the <strong>height</strong> of the building located in the block at row <code>r</code> and column <code>c</code>.</p>
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<p>A city's <strong>skyline</strong> is the the outer contour formed by all the building when viewing the side of the city from a distance. The <strong>skyline</strong> from each cardinal direction north, east, south, and west may be different.</p>
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<p>We are allowed to increase the height of <strong>any number of buildings by any amount</strong> (the amount can be different per building). The height of a <code>0</code>-height building can also be increased. However, increasing the height of a building should <strong>not</strong> affect the city's <strong>skyline</strong> from any cardinal direction.</p>
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<p>Return <em>the <strong>maximum total sum</strong> that the height of the buildings can be increased by <strong>without</strong> changing the city's <strong>skyline</strong> from any cardinal direction</em>.</p>
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<p> </p>
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<p><strong>Example 1:</strong></p>
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<img alt="" src="https://assets.leetcode.com/uploads/2021/06/21/807-ex1.png" style="width: 700px; height: 603px;" />
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<pre>
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<strong>Input:</strong> grid = [[3,0,8,4],[2,4,5,7],[9,2,6,3],[0,3,1,0]]
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<strong>Output:</strong> 35
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<strong>Explanation:</strong> The building heights are shown in the center of the above image.
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The skylines when viewed from each cardinal direction are drawn in red.
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The grid after increasing the height of buildings without affecting skylines is:
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gridNew = [ [8, 4, 8, 7],
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[7, 4, 7, 7],
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[9, 4, 8, 7],
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[3, 3, 3, 3] ]
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</pre>
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<p><strong>Example 2:</strong></p>
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<pre>
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<strong>Input:</strong> grid = [[0,0,0],[0,0,0],[0,0,0]]
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<strong>Output:</strong> 0
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<strong>Explanation:</strong> Increasing the height of any building will result in the skyline changing.
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</pre>
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<p> </p>
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<p><strong>Constraints:</strong></p>
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<ul>
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<li><code>n == grid.length</code></li>
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<li><code>n == grid[r].length</code></li>
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<li><code>2 <= n <= 50</code></li>
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<li><code>0 <= grid[r][c] <= 100</code></li>
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</ul>
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