LeetCode085 Maximal Rectangle

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详细见：leetcode.com/problems/maximal-rectangle

Java Solution: github

package leetcode;import java.util.Stack;/* * Given a 2D binary matrix filled with 0's and 1's,  * find the largest rectangle containing only 1's and return its area.For example, given the following matrix:1 0 1 0 01 0 1 1 11 1 1 1 11 0 0 1 0Return 6. */public class P085_MaximalRectangle {public static void main(String[] args) {//System.out.println(new Solution().maxArea(new int[] {1, 2, 3, 2, 1}));System.out.println(new Solution().maximalRectangle(new char[][] {{'1','0','1','0','0'},{'1','0','1','1','1'},{'1','1','1','1','1'},{'1','0','0','1','0'}}));System.out.println(new Solution().maximalRectangle(new char[][] {{'1'}}));System.out.println(new Solution().maximalRectangle(new char[][] {{'0', '1'},{'1', '0'}}));}/* * AC * 需要多学习栈 * 38 ms */static class Solution {    public int maximalRectangle(char[][] matrix) {    if (matrix == null || matrix.length == 0 || matrix[0].length == 0)    return 0;    int[] heights = new int[matrix[0].length];    int maxArea = 0;    for (int i = 0; i != matrix.length; i ++) {    for (int j = 0; j != heights.length; j ++) {    heights[j] = matrix[i][j] == '1' ? heights[j] + 1 : 0;    }    maxArea = Math.max(maxArea, maxArea(heights));    }        return maxArea;    }    int maxArea(int[] heights) {    if (heights == null || heights.length == 0)    return 0;    int maxArea = 0;    Stack<Integer> stk = new Stack<Integer>();    for (int i = 0; i != heights.length; i ++) {    while (! stk.isEmpty() && heights[i] < heights[stk.peek()]) {    int j = stk.pop();    int k = stk.isEmpty() ? -1 : stk.peek();    maxArea = Math.max(maxArea, (i - k - 1) * heights[j]);    }    stk.add(i);    }    while (! stk.isEmpty()) {    int j = stk.pop();    int k = stk.isEmpty() ? -1 : stk.peek();    maxArea = Math.max(maxArea, (heights.length - k - 1) * heights[j]);    }    return maxArea;    }}}

C Solution: github

/*    url: leetcode.com/problems/maximal-rectangle    AC 6ms 61.54%*/#include <stdio.h>#include <stdlib.h>int _max(int a, int b) {    return a < b ? b : a;}int rect(int* h, int* s, int n) {    int si = 0, i = 0, hv = 0, j = 0, l = 0, a = 0;    for (i = 0; i <= n; i ++) {        hv = i == n ? 0 : h[i];        if (si == 0 || hv > h[s[si - 1]]) {            s[si ++] = i;        } else {            j = s[si - 1];            si --;            l = si == 0 ? i : i - 1 - s[si - 1];            a = _max(a, h[j] * l);            i --;        }    }    return a;}int maximalRectangle(char** m, int rn, int cn) {    int* h = (int*) malloc(sizeof(int) * cn);    int i = 0, j = 0, a = 0;    int* s = (int*) malloc(sizeof(int) * cn);    for (j = 0; j < cn; j ++) h[j] = 0;    for (i = 0; i < rn; i ++) {        for (j = 0; j < cn; j ++)            h[j] = m[i][j] == '0' ? 0 : h[j] + 1;        for (j = 0; j < cn; j ++) s[j] = 0;        a = _max(a, rect(h, s, cn));    }    free(h);    free(s);    return a;}int main() {    char** m = (char**) malloc(sizeof(char*) * 4);    int rn = 4, cn = 5;    m[0] = "10100";    m[1] = "10111";    m[2] = "11111";    m[3] = "10010";    printf("answer is %d\r\n", maximalRectangle(m, rn, cn));    free(m);    return 0;}

Python Solution: github

#coding=utf-8'''    url: leetcode.com/problems/maximal-rectangle    @author:     zxwtry    @email:      zxwtry@qq.com    @date:       2017年4月21日    @details:    Solution: 155ms 64.34%'''class Solution(object):    def count(self, t, tn):        s, sn, i, a = [], 0, 0, 0        while i <= tn:            tv = 0 if i == tn else t[i]            if sn == 0 or t[s[sn-1]] <= tv:                s.append(i)                sn, i = sn+1, i+1            else:                j, sn = s.pop(), sn-1                l = i if sn == 0 else i-1-s[sn-1]                a = max(a, t[j] * l)        return a                    def maximalRectangle(self, m):        """        :type m: List[List[str]]        :rtype: int        """        rn = 0 if m == None else len(m)        if rn == 0: return 0        cn = 0 if m[0] == None else len(m[0])        if cn == 0: return 0        t, a = [0] * cn, 0        for i in range(rn):            for j in range(cn):                if m[i][j] == '1': t[j] += 1                else: t[j] = 0            a = max(a, self.count(t, cn))        return aif __name__ == "__main__":    m = [            ['1','0','1','0','0'],            ['1','0','1','1','1'],            ['1','0','1','1','1'],            ['1','1','1','1','1'],            ['1','1','1','1','1'],            ['1','0','0','1','0'],        ]    print(Solution().maximalRectangle(m))

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