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302. Smallest Rectangle Enclosing Black Pixels

时间:2017-11-26 16:00:31      阅读:172      评论:0      收藏:0      [点我收藏+]

标签:enc   follow   cte   binary   res   osi   length   image   int   

An image is represented by a binary matrix with 0 as a white pixel and 1 as a black pixel. The black pixels are connected, i.e., there is only one black region. Pixels are connected horizontally and vertically. Given the location (x, y) of one of the black pixels, return the area of the smallest (axis-aligned) rectangle that encloses all black pixels.

For example, given the following image:

[

  "0010",

  "0110",

  "0100"

]

and x = 0, y = 2,

 

Return 6.

 

public class Solution {
    public int minArea(char[][] image, int x, int y) {
        if(image == null || image.length == 0) {
            return 0;
        }
        int rowNum = image.length, colNum = image[0].length;
        int left = binarySearch(image, 0, y, 0, rowNum, true, true);
        int right = binarySearch(image, y + 1, colNum, 0, rowNum, true, false);
        int top = binarySearch(image, 0, x, left, right, false, true);
        int bot = binarySearch(image, x + 1, rowNum, left, right, false, false);
        
        return (right - left) * (bot - top);
    }
    
    private int binarySearch(char[][] image, int lo, int hi, int min, int max, boolean searchHorizontal, boolean searchLo) {
        while(lo < hi) {
            int mid = lo + (hi - lo) / 2;
            boolean hasBlackPixel = false;
            for(int i = min; i < max; i++) {
                if((searchHorizontal ? image[i][mid] : image[mid][i]) == 1) {
                    hasBlackPixel = true;
                    break;
                }
            }
            if(hasBlackPixel == searchLo) {
                hi = mid;
            } else {
                lo = mid + 1;
            }
        }
        return lo;
    }
}

 

302. Smallest Rectangle Enclosing Black Pixels

标签:enc   follow   cte   binary   res   osi   length   image   int   

原文地址:http://www.cnblogs.com/jxr041100/p/7899060.html

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