题目：

题解：

int maximalRectangle(char** matrix, int matrixSize, int* matrixColSize) {
    int m = matrixSize;
    if (m == 0) {
        return 0;
    }
    int n = matrixColSize[0];
    int left[m][n];
    memset(left, 0, sizeof(left));
    for (int i = 0; i < m; i++) {
        for (int j = 0; j < n; j++) {
            if (matrix[i][j] == '1') {
                left[i][j] = (j == 0 ? 0 : left[i][j - 1]) + 1;
            }
        }
    }

    int ret = 0;
    for (int i = 0; i < m; i++) {
        for (int j = 0; j < n; j++) {
            if (matrix[i][j] == '0') {
                continue;
            }
            int width = left[i][j];
            int area = width;
            for (int k = i - 1; k >= 0; k--) {
                width = fmin(width, left[k][j]);
                area = fmax(area, (i - k + 1) * width);
            }
            ret = fmax(ret, area);
        }
    }
    return ret;
}